There's a Genshi bundle for TextMate that provides:
- Snippets for expressions and the various template directives,
- Commands for rendering templates, and checking their syntax,
- Templates for creating new Genshi template files.
You can find the bundle here, and check it out from Subversion as follows:
$ svn co http://svn.edgewall.org/repos/genshi/contrib/textmate/Genshi.tmbundle
You can then simply double-click the Genshi.tmbundle folder to install the bundle.