For anyone else who wants to play around with the examples in the gtk2
section of The Ruby Way, but ran into some issues, here's the info you might
need.
I found this page, and followed the directions:
http://ruby-gnome2.sourceforge.jp/hiki.cgi?Install+Guide+for+Windows
I followed the troubleshooting steps, and when that didn't work a Google
search of "GLib-GObject-CRITICAL **:" (which was one of the errors I was
getting) and that led me to this comment by agenteo on the mailing list:
http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/225568
agenteo's solution works 
curiously, I couldn't find it via the ruby kitchen sink searching by "gtk2
install windows more:mailing-lists"