Currently it is generated from Rails 3.0.0 beta 3 version. I will post the updates once the new Rails 3 versions roll out.
Dictionary in Textmate

Installation instructions

Unzip downloaded file into ~/Library/Dictionaries folder if you want to keep this dictionary only for yourself. You may need to create this folder if you haven't installed any dictionaries before.

To make it available for all users, drop the Ruby on Rails 3.0.0b3.dictionary folder into /Library/Dictionaries folder.