Just a quick tip for installing the rSpec bundle for TextMate: it is important that the bundle that you install is synced with the version of rSpec that you are actually running on your machine / in your project. Otherwise you will get a bunch of Ruby errors.
Close TextMate, open up a shell, and go to the bundles directory for your installation, which is probably something like this:
/Users/USER/Library/Application Support/TextMate/Pristine Copy/Bundles/
And then run the following code to pull down the latest (you may want to use a particular tag) from their repo:
svn export http://rspec.rubyforge.org/svn/trunk/RSpec.tmbundle/
Then you can enjoy nice testing by pressing Command-R from within one of your spec files: (IMAGE REMOVED - My blog was hacked and I lost data)