Eventhough I irregularly sneak away from other distractions to tweak on uru, it's showing promise and deserves more than its current lonely home on my disk. Uru's primary goal is to make me happier when I play with ruby, and is going to stay focused on (a) multi-platform easy-of-use, and (b) polishing just a few core features (think micro-kernel) while trying to grow a plugin system.
If you're still reading this and think a go-based-multi-platform-ruby-environment-wrangling-ninja sounds interesting to tweak on, dive into the alpha quality code and see what you can blow up on your Linux, Windows, or OS X system. Here's a post [1] to get you started with go's wonderful integrated cross-compiling toolchain if you're not already familar.