hey,
Ruby is developed under Linux, and is written in fairly straightforward C. It runs under UNIX, DOS, Windows 95/98/NT/2000, Mac OSX, BeOS, Amiga, Acorn Risc OS, and OS/2. There's a MacOS (not X) port of Ruby, by Hisakuni FUJIMOTO at
http://www.imasy.or.jp/~hisa/ruby/macruby.html. However it's based on Ruby 1.1b7, and hasn't been updated since December 1999. It's highly experimental. It may crash and sometimes freeze the OS, even with the sample scripts included in the Ruby distribution.