Small note to self (When I blog about something, I tend to remember it better).
On my new testing environment, I spent over twenty minutes figuring out why some gem would not be available. Once I figured out that somehow I needed to add require 'rubygems' I came to realize that on the new machine, I did not add a certain line to my bashrc, an environment variable was not set. Since my development and production machines have this set, I forgot about it alltogether (when something "just works", why bother more mental effort on the matter?).
Here is the line to be added to your ~/.bashrc:
After that, in all your ruby environments, gems are automatically available when 'require'ing them. More on the matter at stackoverflow.