I just found out about Ruby2CExtension (
http://ruby2cext.rubyforge.org/), and a search of the forum came up empty, so I thought I'd ask if anyone's tried it.
It only works with 1.8.x (1.8.4 or later, I think), but it could make a Ruby game a bit faster while also adding another layer of obfuscation to a distributed (commercial?) game.
I put it in my todo list, and I'll try to update this thread when I get around to testing it (if anyone cares).