My Setup

development.log

MONGODB example-development['system.namespaces'].find({})
MONGODB example-development['system.namespaces'].find({})
MONGODB example-development['system.namespaces'].find({})
MONGODB example-development['system.namespaces'].find({})
MONGODB example-development['system.namespaces'].find({})
MONGODB example-development['system.namespaces'].find({})
MONGODB example-development['system.namespaces'].find({})
MONGODB example-development['system.namespaces'].find({})
MONGODB example-development['system.namespaces'].find({})
MONGODB example-development['system.namespaces'].find({})
MONGODB example-development['system.namespaces'].find({})
MONGODB example-development['system.namespaces'].find({})
MONGODB example-development['system.namespaces'].find({})
MONGODB example-development['system.namespaces'].find({})
MONGODB example-development['system.namespaces'].find({})
MONGODB example-development['system.namespaces'].find({})
MONGODB example-development['system.namespaces'].find({})
MONGODB example-development['system.namespaces'].find({})
MONGODB example-development['system.namespaces'].find({})
MONGODB example-development['system.namespaces'].find({})
MONGODB example-development['system.namespaces'].find({})
MONGODB example-development['system.namespaces'].find({})
MONGODB example-development['system.namespaces'].find({})
MONGODB example-development['system.namespaces'].find({})
MONGODB example-development['system.namespaces'].find({})
MONGODB example-development['system.namespaces'].find({})
MONGODB example-development['system.namespaces'].find({})
MONGODB example-development['system.namespaces'].find({})
MONGODB example-development['system.namespaces'].find({})
MONGODB example-development['system.namespaces'].find({})
MONGODB example-development['system.namespaces'].find({})
MONGODB example-development['system.namespaces'].find({})
MONGODB example-development['system.namespaces'].find({})
### Then I hit ctrl-c to cancel Page.first call ###

Gemfile

source 'http://rubygems.org'

gem 'rails', '>= 3.1.0'

gem 'activemerchant', :git => "git://github.com/quadule/active_merchant.git"
#gem 'exact4r', '>= 1.4'

#Rails enhancements
gem "responders"
gem 'inherited_resources', '~> 1.2.1'
gem 'app_config'

gem 'draper'
gem 'draper-cancan'

#Database stuff
gem "mongoid"#, '2.2.1'
gem "mongoid-paperclip", :require => "mongoid_paperclip"
gem 'mongoid_search'
gem 'bson_ext'
gem 'mongoid_slug'

gem 'paperclip'

#PDF generation
gem 'wicked_pdf'

#Maps related items
gem 'googlestaticmap'

#AUTH and PERMISSIONS
gem 'devise'
gem 'cancan'

#Analytics
gem 'analytical'

#BACKGROUND JOB
gem 'delayed_job'
gem 'delayed_job_mongoid'

#Assets
group :assets do  
  gem 'sass-rails', " ~> 3.1.0"  
  gem 'coffee-rails', " ~> 3.1.0"  
  gem 'uglifier'
  gem 'compass', :git => 'git://github.com/chriseppstein/compass.git'
end

#UI
gem 'css3buttons', :git => 'git://github.com/thetron/css3buttons_rails_helpers.git'
gem 'slim'
gem 'simple_form'
gem "ckeditor", "~> 3.5.4"
gem 'responders'
gem 'kaminari' #paging
gem 'redcarpet'
gem 'has_scope'

#Javacript Libraries
gem 'right-rails'
gem 'modernizr-rails'

#DEPLOYMENT
gem 'capistrano'

#Other
gem "json", :platforms => :ruby_18

#Metrics
gem 'rpm_contrib'
gem 'newrelic_rpm'

#Application Improvements
gem 'hoptoad_notifier'
gem 'sendgrid'
gem 'fastercsv'
gem 'gibbon' #interactions with mailchimp

#Debugger
#gem "ruby-debug", :group => [:development, :test] #Doesn't work in ruby 1.9.x yet


#Not sure what uses this gem, but I'm getting a notice:
gem 'SystemTimer', :platforms => :ruby_18


gem 'rspec-rails', '>=2.0.0', :group => [:development, :test]

group :development do
  gem "rails3-generators"
  gem 'pry'
  gem 'pry-doc'
  gem 'active_reload'
  gem 'rails-footnotes', :git => "git://github.com/josevalim/rails-footnotes.git"
end

group :test do
  gem 'factory_girl_rails'
  gem 'delorean'
  gem 'mocha'
  gem 'mongoid-rspec'
  gem 'remarkable_mongoid'
  gem 'capybara'
  gem 'database_cleaner'
  gem 'cucumber'
  gem 'cucumber-rails'
  gem 'launchy'
  gem 'vcr'
  gem 'webmock'
  gem 'email_spec'
  
  gem 'rb-fsevent', :require => false
  gem 'growl'
  gem 'guard-bundler'
  gem 'guard-cucumber'
  gem 'guard-livereload'
  gem 'guard-pow'
  gem 'guard-rspec'
end

mongoid.yml

development:
  host: localhost
  database: example-development
  preload_models: false
  raise_not_found_error: true
  allow_dynamic_fields: false
  include_root_in_json: false
  parameterize_keys: true
  persist_in_safe_mode: false
  autocreate_indexes: false
  reconnect_time: 3
  
  
staging:
  host: localhost
  database: example-staging
  raise_not_found_error: true
  allow_dynamic_fields: false
  include_root_in_json: false
  parameterize_keys: true
  persist_in_safe_mode: false
  autocreate_indexes: false
  reconnect_time: 3
  

test:
  host: localhost
  database: example-test
  preload_models: false
  raise_not_found_error: true
  allow_dynamic_fields: false
  include_root_in_json: false
  parameterize_keys: true
  persist_in_safe_mode: false
  autocreate_indexes: false
  reconnect_time: 3
  
  
cucumber:
  host: localhost
  database: example-test
  raise_not_found_error: true
  allow_dynamic_fields: false
  include_root_in_json: false
  parameterize_keys: true
  persist_in_safe_mode: false
  autocreate_indexes: false
  reconnect_time: 3
  

# set these environment variables on your prod server
production:
  host: localhost
  database: example-production
  raise_not_found_error: true
  allow_dynamic_fields: false
  include_root_in_json: false
  parameterize_keys: true
  persist_in_safe_mode: false
  autocreate_indexes: false
  reconnect_time: 3

Rails Console

pry(main)> Account.first
^CInterrupt: 
from /Users/andrew/code/rails_apps/example/vendor/ruby/1.9.1/gems/mongo-1.4.1/lib/mongo/connection.rb:938:in `read'
pry(main)> Page.first
Mongo::ConnectionFailure: Expected response 5406 but got 2293861
from /Users/andrew/code/rails_apps/example/vendor/ruby/1.9.1/gems/mongo-1.4.1/lib/mongo/connection.rb:790:in `receive_header'
pry(main)> Page.first
^CInterrupt: 
from /Users/andrew/code/rails_apps/example/vendor/ruby/1.9.1/gems/bson-1.4.1/lib/bson/bson_c.rb:28:in `deserialize'
pry(main)> Page.first
Mongo::ConnectionFailure: Expected response 16381 but got 1900645
from /Users/andrew/code/rails_apps/example/vendor/ruby/1.9.1/gems/mongo-1.4.1/lib/mongo/connection.rb:790:in `receive_header'
pry(main)> Page.first
^CInterrupt: 
from /Users/andrew/code/rails_apps/example/vendor/ruby/1.9.1/gems/mongo-1.4.1/lib/mongo/connection.rb:938:in `read'
pry(main)> Page.first
Mongo::ConnectionFailure: Expected response 24794 but got 4587621
from /Users/andrew/code/rails_apps/example/vendor/ruby/1.9.1/gems/mongo-1.4.1/lib/mongo/connection.rb:790:in `receive_header'
pry(main)> Page.first
^CInterrupt: 
from /Users/andrew/code/rails_apps/example/vendor/ruby/1.9.1/gems/mongo-1.4.1/lib/mongo/connection.rb:938:in `read'
pry(main)> Page.first
Mongo::ConnectionFailure: Expected response 27988 but got 1701052416
from /Users/andrew/code/rails_apps/example/vendor/ruby/1.9.1/gems/mongo-1.4.1/lib/mongo/connection.rb:790:in `receive_header'
pry(main)> Page.first
^CInterrupt: 
from /Users/andrew/code/rails_apps/example/vendor/ruby/1.9.1/gems/bson-1.4.1/lib/bson/bson_c.rb:28:in `deserialize'

running User.first

bundle exec rails runner User.first
^C/Users/andrew/code/rails_apps/example/vendor/ruby/1.9.1/gems/railties-3.1.1/lib/rails/commands/runner.rb:49:in `eval': /Users/andrew/code/rails_apps/example/vendor/ruby/1.9.1/gems/bson-1.4.1/lib/bson/byte_buffer.rb:29:in `initialize':  (Interrupt)
	from /Users/andrew/code/rails_apps/example/vendor/ruby/1.9.1/gems/bson-1.4.1/lib/bson/bson_c.rb:28:in `new'
	from /Users/andrew/code/rails_apps/example/vendor/ruby/1.9.1/gems/bson-1.4.1/lib/bson/bson_c.rb:28:in `deserialize'
	from /Users/andrew/code/rails_apps/example/vendor/ruby/1.9.1/gems/mongo-1.4.1/lib/mongo/connection.rb:829:in `read_documents'
	from /Users/andrew/code/rails_apps/example/vendor/ruby/1.9.1/gems/mongo-1.4.1/lib/mongo/connection.rb:776:in `receive'
	from /Users/andrew/code/rails_apps/example/vendor/ruby/1.9.1/gems/mongo-1.4.1/lib/mongo/connection.rb:494:in `block in receive_message'
	from <internal:prelude>:10:in `synchronize'
	from /Users/andrew/code/rails_apps/example/vendor/ruby/1.9.1/gems/mongo-1.4.1/lib/mongo/connection.rb:492:in `receive_message'
	from /Users/andrew/code/rails_apps/example/vendor/ruby/1.9.1/gems/mongo-1.4.1/lib/mongo/cursor.rb:470:in `block in send_initial_query'
	from /Users/andrew/code/rails_apps/example/vendor/ruby/1.9.1/gems/mongo-1.4.1/lib/mongo/util/logging.rb:23:in `instrument'
	from /Users/andrew/code/rails_apps/example/vendor/ruby/1.9.1/gems/mongo-1.4.1/lib/mongo/cursor.rb:468:in `send_initial_query'
	from /Users/andrew/code/rails_apps/example/vendor/ruby/1.9.1/gems/rpm_contrib-2.1.4/lib/rpm_contrib/instrumentation/mongo.rb:35:in `refresh_with_newrelic_trace'
	from /Users/andrew/code/rails_apps/example/vendor/ruby/1.9.1/gems/mongo-1.4.1/lib/mongo/cursor.rb:128:in `next'
	from /Users/andrew/code/rails_apps/example/vendor/ruby/1.9.1/gems/mongo-1.4.1/lib/mongo/cursor.rb:290:in `each'
	from /Users/andrew/code/rails_apps/example/vendor/ruby/1.9.1/gems/mongo-1.4.1/lib/mongo/db.rb:229:in `collect'
	from /Users/andrew/code/rails_apps/example/vendor/ruby/1.9.1/gems/mongo-1.4.1/lib/mongo/db.rb:229:in `collection_names'
	from /Users/andrew/code/rails_apps/example/vendor/ruby/1.9.1/gems/mongo-1.4.1/lib/mongo/db.rb:280:in `create_collection'
	from /Users/andrew/code/rails_apps/example/vendor/ruby/1.9.1/bundler/gems/mongoid-ff0580ce736f/lib/mongoid/collections/master.rb:41:in `initialize'
	from /Users/andrew/code/rails_apps/example/vendor/ruby/1.9.1/bundler/gems/mongoid-ff0580ce736f/lib/mongoid/collection.rb:127:in `new'
	from /Users/andrew/code/rails_apps/example/vendor/ruby/1.9.1/bundler/gems/mongoid-ff0580ce736f/lib/mongoid/collection.rb:127:in `master'
	from /Users/andrew/code/rails_apps/example/vendor/ruby/1.9.1/bundler/gems/mongoid-ff0580ce736f/lib/mongoid/collection.rb:60:in `find_one'
	from /Users/andrew/code/rails_apps/example/vendor/ruby/1.9.1/bundler/gems/mongoid-ff0580ce736f/lib/mongoid/contexts/mongo.rb:161:in `first'
	from /Users/andrew/code/rails_apps/example/vendor/ruby/1.9.1/bundler/gems/mongoid-ff0580ce736f/lib/mongoid/criteria.rb:43:in `one'
	from /Users/andrew/code/rails_apps/example/vendor/ruby/1.9.1/bundler/gems/mongoid-ff0580ce736f/lib/mongoid/criterion/inclusion.rb:127:in `find'
	from /Users/andrew/code/rails_apps/example/vendor/ruby/1.9.1/bundler/gems/mongoid-ff0580ce736f/lib/mongoid/finders.rb:84:in `find'
	from /Users/andrew/code/rails_apps/example/vendor/ruby/1.9.1/bundler/gems/mongoid-ff0580ce736f/lib/mongoid/finders.rb:122:in `first'
	from (eval):1:in `<top (required)>'
	from /Users/andrew/code/rails_apps/example/vendor/ruby/1.9.1/gems/railties-3.1.1/lib/rails/commands/runner.rb:49:in `eval'
	from /Users/andrew/code/rails_apps/example/vendor/ruby/1.9.1/gems/railties-3.1.1/lib/rails/commands/runner.rb:49:in `<top (required)>'
	from /Users/andrew/code/rails_apps/example/vendor/ruby/1.9.1/gems/railties-3.1.1/lib/rails/commands.rb:63:in `require'
	from /Users/andrew/code/rails_apps/example/vendor/ruby/1.9.1/gems/railties-3.1.1/lib/rails/commands.rb:63:in `<top (required)>'
	from script/rails:6:in `require'
	from script/rails:6:in `<main>'

bundle exec rails runner User.first  155.45s user 39.36s system 85% cpu 3:48.50 total

rvm.info

ruby-1.9.3-rc1:

  system:
    uname:       "Darwin Andrew-Kaleks-MacBook-Pro.local 11.2.0 Darwin Kernel Version 11.2.0: Tue Aug  9 20:54:00 PDT 2011; root:xnu-1699.24.8~1/RELEASE_X86_64 x86_64"
    bash:        "/bin/bash => GNU bash, version 3.2.48(1)-release (x86_64-apple-darwin11)"
    zsh:         "/bin/zsh => zsh 4.3.11 (i386-apple-darwin11.0)"

  rvm:
    version:      "rvm 1.8.6 by Wayne E. Seguin (wayneeseguin@gmail.com) [https://rvm.beginrescueend.com/]"

  ruby:
    interpreter:  "ruby"
    version:      "1.9.3dev"
    date:         "2011-09-23"
    platform:     "x86_64-darwin11.1.0"
    patchlevel:   "2011-09-23 revision 33323"
    full_version: "ruby 1.9.3dev (2011-09-23 revision 33323) [x86_64-darwin11.1.0]"

  homes:
    gem:          "/Users/andrew/.rvm/gems/ruby-1.9.3-rc1"
    ruby:         "/Users/andrew/.rvm/rubies/ruby-1.9.3-rc1"

  binaries:
    ruby:         "/Users/andrew/.rvm/rubies/ruby-1.9.3-rc1/bin/ruby"
    irb:          "/Users/andrew/.rvm/rubies/ruby-1.9.3-rc1/bin/irb"
    gem:          "/Users/andrew/.rvm/rubies/ruby-1.9.3-rc1/bin/gem"
    rake:         "/Users/andrew/.rvm/gems/ruby-1.9.3-rc1/bin/rake"

  environment:
    PATH:         "/Users/andrew/.rvm/gems/ruby-1.9.3-rc1/bin:/Users/andrew/.rvm/gems/ruby-1.9.3-rc1@global/bin:/Users/andrew/.rvm/rubies/ruby-1.9.3-rc1/bin:/Users/andrew/.rvm/bin:/Users/andrew/bin:/Users/andrew/.bin:/usr/local/homebrew/bin:/usr/local/bin:/usr/local/sbin:/usr/local/mysql/bin:/usr/local/git/bin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/X11/bin"
    GEM_HOME:     "/Users/andrew/.rvm/gems/ruby-1.9.3-rc1"
    GEM_PATH:     "/Users/andrew/.rvm/gems/ruby-1.9.3-rc1:/Users/andrew/.rvm/gems/ruby-1.9.3-rc1@global"
    MY_RUBY_HOME: "/Users/andrew/.rvm/rubies/ruby-1.9.3-rc1"
    IRBRC:        "/Users/andrew/.rvm/rubies/ruby-1.9.3-rc1/.irbrc"
    RUBYOPT:      ""

This is in reference to: https://github.com/mongoid/mongoid/issues/1375
Issue ended up being: rpm_contrib. Removing it fixed it.