gistfile1.txt

[root@VIRT-V2V:/opt/veewee] $ irb
1.9.2p320 :001 > require 'ruby-libvirt'
LoadError: no such file to load -- ruby-libvirt
  from (irb):1:in `require'
	from (irb):1
	from /usr/local/rvm/rubies/ruby-1.9.2-p320/bin/irb:16:in `<main>'
1.9.2p320 :002 > require 'libvirt'
LoadError: no such file to load -- libvirt
	from (irb):2:in `require'
	from (irb):2
	from /usr/local/rvm/rubies/ruby-1.9.2-p320/bin/irb:16:in `<main>'
1.9.2p320 :003 >

ruby and gem seem to come from the right place:

[root@VIRT-V2V:/opt/veewee] $ which gem
/usr/local/rvm/rubies/ruby-1.9.2-p320/bin/gem
[root@VIRT-V2V:/opt/veewee] $ which ruby
/usr/local/rvm/rubies/ruby-1.9.2-p320/bin/ruby
[root@VIRT-V2V:/opt/veewee] $ gem list | grep ruby
libxml-ruby (2.6.0)
ruby-hmac (0.4.0)
ruby-libvirt (0.4.0)
ruby-vnc (1.0.1)
rubygems-bundler (1.1.1)

Can add thor though:

rubyntlm (0.1.1)
1.9.2p320 :001 > require "thor"
 => true

Gem path:

1.9.2p320 :004 > puts Gem.path
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee
/usr/local/rvm/gems/ruby-1.9.2-p320@global
 => nil

I believe this means that rubygems is loaded already:

1.9.2p320 :009 > require 'rubygems'
 => false

gem env:

[root@VIRT-V2V:/opt/veewee] $ gem env
RubyGems Environment:
  - RUBYGEMS VERSION: 1.8.25
  - RUBY VERSION: 1.9.2 (2012-04-20 patchlevel 320) [x86_64-linux]
  - INSTALLATION DIRECTORY: /usr/local/rvm/gems/ruby-1.9.2-p320@veewee
  - RUBY EXECUTABLE: /usr/local/rvm/rubies/ruby-1.9.2-p320/bin/ruby
  - EXECUTABLE DIRECTORY: /usr/local/rvm/gems/ruby-1.9.2-p320@veewee/bin
  - RUBYGEMS PLATFORMS:
    - ruby
    - x86_64-linux
  - GEM PATHS:
     - /usr/local/rvm/gems/ruby-1.9.2-p320@veewee
     - /usr/local/rvm/gems/ruby-1.9.2-p320@global
  - GEM CONFIGURATION:
     - :update_sources => true
     - :verbose => true
     - :benchmark => false
     - :backtrace => false
     - :bulk_threshold => 1000
  - REMOTE SOURCES:
     - http://rubygems.org/

though ruby-libvirt doesn't appear here:

1.9.2p320 :014 > puts $:
/opt/veewee/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/vagrant-0.5.4/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/virtualbox-0.7.5/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/thor-0.17.0/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/ruby-vnc-1.0.1/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/rspec-2.13.0/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/rspec-mocks-2.13.0/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/rspec-expectations-2.13.0/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/rspec-core-2.13.0/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/progressbar-0.20.0/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/popen4-0.1.2/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/open4-1.3.0/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/mario-0.0.6/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/json-1.7.7/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/i18n-0.6.4/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/highline-1.6.15/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/grit-2.5.0/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/posix-spawn-0.3.6/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/fog-1.9.0/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/ruby-hmac-0.4.0/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/net-scp-1.0.4/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/net-ssh-2.2.0/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/multi_json-1.6.1/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/mime-types-1.21/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/formatador-0.2.4/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/fission-0.4.0/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/excon-0.20.0/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/erubis-2.7.0/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/bundler/gems/em-winrm-31745601d3dd/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/winrm-1.1.2/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/savon-0.9.5/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/wasabi-1.0.0/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/nori-1.1.5/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/httpi-0.9.7/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/rack-1.5.2/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/rubyntlm-0.1.1/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/logging-1.6.2/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/little-plugger-1.1.3/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/httpclient-2.2.0.2/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/gssapi-1.0.3/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/uuidtools-2.1.3/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/mixlib-log-1.4.1/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/eventmachine-1.0.0.beta.3/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/diff-lcs-1.2.1/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/childprocess-0.3.9/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/ffi-1.4.0/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/ffi-1.4.0/ext/ffi_c
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/archive-tar-minitar-0.5.2/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/ansi-1.3.0/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/akami-1.2.0/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/nokogiri-1.5.6/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/gyoku-1.0.0/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/builder-3.2.0/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/Platform-0.4.0/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/CFPropertyList-2.0.17/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@veewee/gems/libxml-ruby-2.6.0/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@global/gems/rake-10.0.3/lib
/usr/local/rvm/gems/ruby-1.9.2-p320@global/gems/bundler-1.3.1/lib
/usr/local/rvm/rubies/ruby-1.9.2-p320/lib/ruby/site_ruby/1.9.1
/usr/local/rvm/rubies/ruby-1.9.2-p320/lib/ruby/site_ruby/1.9.1/x86_64-linux
/usr/local/rvm/rubies/ruby-1.9.2-p320/lib/ruby/site_ruby
/usr/local/rvm/rubies/ruby-1.9.2-p320/lib/ruby/vendor_ruby/1.9.1
/usr/local/rvm/rubies/ruby-1.9.2-p320/lib/ruby/vendor_ruby/1.9.1/x86_64-linux
/usr/local/rvm/rubies/ruby-1.9.2-p320/lib/ruby/vendor_ruby
/usr/local/rvm/rubies/ruby-1.9.2-p320/lib/ruby/1.9.1
/usr/local/rvm/rubies/ruby-1.9.2-p320/lib/ruby/1.9.1/x86_64-linux
 => nil