Experience with PL/xx?

Hi,

does anybody out there have experience with the several PL's which are
available for PostgreSQL? I am currently evaluating several databases
(commercial as well as free & open source) for a new project and would
just like to hear some feedback.

PL/Java seems to be developed by a fairly small team - no updates on
their website since December 2002 (and even what's available on this
web site is not very encouraging to use PL/Java on a production
system). Does anybody use PL/Java?

What about PL/Python or PL/Ruby? Any experience with these two
implementations on a production system? Are there any PostgreSQL
specifics or limitations? Significant differences between these two
languages?

Any input will be apprecíated,

Klaus