I’ve put together a Universal (i.e. runs on both ppc and i386 architectures) binary version of ruby, intended for developers of Ruby apps who want to ensure that their applications run on both old and new Macs.
It’s only really going to be useful to those people who write ruby code which relies on something binary underneath–any of the bundles (shared libraries) that come with ruby, for example. On the other hand, it also just happens to be a distribution of the latest version of ruby (1.8.4), pre-compiled and ready to go. The current Mac OS X version is 1.8.2.