With Ruby on Rails 2.0.2 fresh out of the gates and hordes of (us) DHH fanboys coding away in Textmate on their Macs will soon realize that the new .rhtml template is now .html.erb. This file extension isn’t recognized as Rails (HTML) by default in Textmate 1.5.7.
All you need to do is edit the correct Textmate Bundle which you get to by finding in the Textmate Menu: Bundles -> Bundle Editor -> Show Bundle Editor -> click the arrow beside Ruby on Rails -> near the bottom of the list click on Rails (HTML), then on the right hand side area find:
fileTypes = ( 'rhtml' );
and change it to:
fileTypes = ( 'rhtml', 'erb' );
Greg is the man and posted the original fix to the Textmate html.erb bundle problem.