It's been done. See these search results:

  http://groups-beta.google.com/group/comp.lang.ruby/search?q=zaurus&

However, I think this platform has rather limited memory -- difficult
to do a "fat" Ruby install. And I think the GUI is fairly proprietary
(as with most PDAa) so I don't know if there are Ruby bindings
for it.


Cheers,
Hal