Though there were no solutions submitted this week, we learned of
gamebox[1] a framework built on top of Rubygame[2] to spring board
game development. I would also recommend checking out Gosu[3] as well
if you are interested in other game development tools for Ruby.

There is also a solution by James Edward Gray II from 2004[4].

[1]: http://github.com/shawn42/gamebox/tree/master
[2]: http://rubygame.org/
[3]: http://code.google.com/p/gosu/
[4]: http://osdir.com/ml/lang.perl.qotw.discuss/2004-09/msg00138.html