There have been a hand full of releases since I have posted an announcement here. Since then, I have implemented a simple ERB-based template output mode, in lieu of the StringTemplate-based template mode provided by ANTLR's Java and Python targets. I have also fixed several bugs, made a number of code tweaks, and authored a significant amount of usage and API documentation.

Gem installation: gem install antlr3
Homepage: http://antlr.ohboyohboyohboy.org
Rubygems.org: http://rubygems.org/gems/antlr3
GitHub: http://github.com/ohboyohboyohboy/antlr3