tl:dr Go here if you have an issue with Textmate using the wrong version of Ruby.
I like to tinker with programming merely as a hobby, besides learning iOS programming I have been wanting to learn one of the web language/framework combos out there. After much waffling between Python/Django and Ruby/Rails, I went with Ruby.
I purchased a copy of “Learn Ruby the Hard Way” and began to dig in. The book wants you to use a text editor named gedit, which I’m sure works great, but I want to use Textmate. I like using Textmate for anything I don’t have to do in Xcode. The issue I ran into was Textmate was using the default version of Ruby installed on Snow Leopard, 1.8.7, instead of the version I just upgraded to using the lovely and simple to use Ruby Version Manager (RVM).
After googling around and trying multiple things, including adding the TM_RUBY entry to Textmate pointing to the location where RVM installs its files, ~/.rvm/bin, but no luck. After a bit more searching I stumbled upon a very helpful Ruby blog with exactly what I was missing. There is an rvm wrapper command that you have to run to get Textmate to use a version of Ruby installed by the RVM instead of the system default.
Huzzah, I’m back in business, thank you interwebs.