Isolate is a very simple RubyGems sandbox. It provides a way to express and install your code's Gem dependencies. When Isolate runs, it uses GEM_HOME, GEM_PATH, and a few other tricks to completely separate your code from the system's RubyGems configuration, leaving it free to run in blissful solitude. While Isolate doesn't make any assumptions about what sort of code you're writing, it was extracted from a few Rails apps, so it's naturally going to be most useful with stuff like Rails, Merb, or Sinatra. Isolate is very, very, very stupid simple. For a much more full-featured Gem bundler, check out Yehuda Katz and Carl Lerche's Bundler[http://github.com/wycats/bundler]: It does a lot of fancy AOT dependency resolution, supports non-gem resources, and is probably a better fit for you. For a widely used Gem manager and installer, check out Chad Woolley's GemInstaller[http://geminstaller.rubyforge.org]. YMMV, but I haven't tried Isolate with anything older than RubyGems 1.3.5.
Gemfile gem 'isolate', '~> 1.3.0'
install gem install isolate -v 1.3.0