bundle.sh

#!/bin/bash                                      
# requires Rubygems 1.3.5, using JRuby 1.4.0     
                                                 
jruby -S gem bundle                              
cd .gems                                         
jar -cf ../WEB-INF/lib/gems.jar bundler_gems     
cd ..                                            

Gemfile

# bundle everything into .gems (won't be uploaded)
disable_rubygems                   
bundle_path '.gems/bundler_gems'   
                                   
gem "rack", "1.0.0"                
gem "dm-appengine"                 
gem "sinatra"                      
gem "haml"                         

. . .

guestbook.rb

# load gems from the jar file
require 'bundler_gems/environment'               
require 'sinatra'                                
require 'dm-core'                                
require 'haml'                                   
                                                 
configure do                                     
  DataMapper.setup(:default, "appengine://auto") 
end                                              

. . .

Notes

In the Gemfile, I set the bundle_path to ".gems/bundler_gems",
then I require "bundler_gems/environment" from inside my app.
This way my app only loads the environment.rb from my jar file.
When I jar it all up, I skip the ".gems" dir, starting one dir lower.

When people say disable_rubygems, we can assume they want
us to toss the rubygems jar. I have no idea how we keep people
from messing with the defaults. Maybe we generate a Gemfile,
with some instructions, and a terse explainaton on the system

config.ru
guestbook.rb
bundle.sh     # will be replaced by appcfg.rb gem
Gemfile
.gems         # skipped during upload process
WEB-INF
|-- web.xml
|-- appengine-web.xml
`--lib
   |-- appengine-jruby-0.0.5.jar
   |-- jruby-rack-0.9.5.jar
   |-- gems.jar
   `-- appengine-api-1.0-sdk-1.2.6.jar