@VoodooLogic I’m one of the maintainers of the Twitter gem and would be happy to answer any specific questions you have while writing your Twitter application.
To start, I would recommend reading the Beginner’s Guide to OAuth, since accessing most of the Twitter API requires authentication.
Once you understand OAuth, I’d recommend browsing the examples that are included with the gem.
Here’s one of my favorite Twitter gem one-liners that doesn’t require OAuth, courtesy of Patrick Ewing (you must first require the gem, as described in @johnpowell‘s answer):
puts Twitter::Search.new(“marry me”).to(“justinbieber”).collect{|tweet| tweet.text}
I would also refer you to two Google Groups. First, the group for the gem, which contains answers to many previously-asked questions about getting started. The second is Twitter API Announcements, which contains important announcements about changes to the API.