Development environment

You need Ruby, doh!

Currently (12/2011) either 1.8.7 or 1.9.x will do but recommended is 1.9.2 or better.

Windows users get RubyInstaller and pick the appropriate version. Also install Devkit to be able to compile C extensions.

Debian based users probably need to update the rubygems version to something current (1.8.x) install rvm and then use it to setup the Ruby version of your choosing

OS X users update the standard Ruby rubygems version with sudo gem update --system and install rvm

Once you have a working Ruby with a modern rubygems version do gem install rake bundler