Preview Video! http://youtu.be/JEYJFGrUypo?a
Google Code Project Page: http://code.google.com/p/sm-ssc/
(yes this picture is out of date now lol)
We are currently at v1.0 rc1 (2010/06/30). See the new thread to follow along.
It should be noted: this build of StepMania is not entirely end-user friendly right now. It can be used, though, assuming you have some knowledge of dealing with StepMania already (installing songs, themes, etc.). :)