I put together my first ruby gem today (for internal use at work). Here is a good tutorial on how to do it. Or else look at chapter 17 in the Pickaxe book. Simply make a gemspec file, define a few attributes listing and describing your files and then compile it. It was astoundingly easy and such a clean way to handle versioning and distributing Ruby code. I always had some weird impression that rubygems was clunkier than Perl's CPAN, but I think I had it wrong. Not at all hard to use.
Setting the RUBYOPT environment variable to 'rubygems' lets you get away with doing a
require on gem-provided modules without doing
require 'rubygems' in every program you write. I'm sure I must've set RUBYOPT myself a year ago on this machine and forgotten. I was sort of wondering one day, hey, how is Ruby finding those modules? This kind of thing is good to know when you need to set up a Ruby environment on someone else's computer in the near future, I imagine. This is one bad thing about having a computer that doesn't need to be reformatted every six months. Who knows how many other tweaks I've done on this machine and forgot about and now silently depend on.