I did a fresh install of cygwin by downloading and then installing the cygwin ports packages by following the directions at http://sourceware.org/cygwinports/ .  I then try and run a Ruby/GTK2 hello world script and it fails on the "require 'gtk2'" line.  Here is a simple form of the require call with the error:

bash-3.2$ ruby -e "require 'gtk2'"
/usr/lib/ruby/site_ruby/1.8/i386-cygwin/gtk2.so: No such file or directory - /usr/lib/ruby/site_ruby/1.8/i386-cygwin/gtk2.so (LoadError)
        from /usr/lib/ruby/site_ruby/1.8/gtk2/base.rb:19
        from /usr/lib/ruby/site_ruby/1.8/gtk2.rb:11:in `require'
        from /usr/lib/ruby/site_ruby/1.8/gtk2.rb:11
        from -e:1:in `require'
        from -e:1

The .so file is in the right place.

bash-3.2$ ls -l /usr/lib/ruby/site_ruby/1.8/i386-cygwin/gtk2.so
-rwxr-x---+ 1 root Users 794112 Dec 18  2008 /usr/lib/ruby/site_ruby/1.8/i386-cygwin/gtk2.so

Does anyone have any ideas on how I might fix this?