Using textmate with rvm

textmate_rvm.sh

#generate a wrapper script for a textmate_ruby - you can call it whatever you like but
#textmate_ruby is clear

rvm wrapper ruby-1.9.2@rails3 textmate

# this will generate a textmate_ruby command for you
# problem with the above is, it's not going use your project specific gemset and ruby
# to do that, edit the file and change the contents to what's below

vi `which textmate_ruby`

#---------- New content --------
#!/usr/bin/env bash 

source ~/.rvm/scripts/rvm
cd .
exec ruby "$@"
#-------------------------------

# set the TM_RUBY textmate environment variable to point to the output of 
# which textmate_ruby
# restart textmate.  have fun

If textmate ack fails after this, here's the fix

http://keep12on.com/2010/04/02/ack-in-project-textmate-bundle-fails-with-ruby-1-9/