[tenderlove]

While RUM is out of date, I still think it's an excellent resource. Some of the information in the book may be out of date, but I think it's an excellent place to start when you want to jump in to Ruby's source. Basically, after reading RUM the best place to go is to start reading the source.

That said, it would be really great if Pat (or someone besides me) published an update version of RUM