I'm testing out ruby using TextMate and seems like it's not picking up my RVM environment SO, here's what i found out.

After you have a functioning rvm setup, all you need to do is as follows:

• Open your terminal (I use iTerm2) and run which rvm-auto-ruby which currently gives me /Users/psyco-mantis/.rvm/bin/rvm-auto-ruby.
• Go to TextMate > Preferences > Variables and add a variable called TM_RUBY and assign the path given in the previous step (Mine was /Users/psyco-mantis/.rvm/bin/rvm-auto-ruby).

Profit!, now if you create a file with puts RUBY_VERSION as the content, you'll see your RVM's ruby version.