While going back through an improving some initialization code of our application I moved all require statements for our rails gems into the Rails::Initializer block. This worked great for everyone except one of my coworkers who reported the following error:

c:/ruby/lib/ruby/site_ruby/1.8/rubygems/version.rb:237:in `initialize': undefined method `collect' for #<Gem::Version::Requirement:0x371b2d8> (NoMethodError)

The solution turned out to be very simple. He just needed to update his rubygems installation (gem update --system) and everything went back to working fine.