Hackety Hack has just released V1.0 of their interactive tutorial for learning the Ruby programming language. HH, combined with its corollary Shoes (a GUI dev toolkit) will get you coding with Ruby in no time.
Check out their new website for information and downloads.
While their approach is unorthodox and seems geared toward the pre-college crowd, HH provides a way for hardware hackers inexperienced with a desktop programming language to develop intelligent GUI based programs to interact with embedded systems. For example, there is a Ruby serialport library separately available.
If nothing else, it gives the kids a new toy to play with!