For those interested, I extracted HotCocoa::Graphics, started cleaning it up, added some specs and examples so you can enjoy the nice DSL built on top of Core Graphics.
Feel free to fork and play with the repo: http://github.com/mattetti/macruby_graphics

Examples and output in the readme. If you don't feel like contributing code, contributing examples and documentation would be awesome!

- Matt

p.s: it's s work in progress and it will probably take me a little while before I get  decent code coverage. Also, Ryan David, note that  used minitest ;)