WARNING: Rails 3.0 is currently in beta. This means that there are probably bugs and that you should "report them":http://rails.lighthouseapp.com/projects/8994-ruby-on-rails/overview if you see them. You also may not want to run the NORAD nuclear launch application off a beta version. But if you're starting development on a new application and you don't mind getting wind in your hair, please do jump on board!
-TIP: To install the Rails 3 prerelease beta using rubygems you have to install all the Rails dependencies first as these will not be installed for you by rubygems: