Currently working on kahakai, working w/ Michael Brailsford to set up Ruby scripting.
So far I'm enjoying the work quite a bit, and although the code is currently only in the design stage, things look pretty promising. The Python scripts are pretty near code-complete, so my experience working with that language has helped out quite a bit in seeing one approach.
I'm using RDoc, of course, and suggestions on the design are always welcome.