I have recently fixed the configure script to recognize Python 3.0. But
note that building and running PL/Python with Python 3.0 does not
actually work. It looks like several symbols have been removed or
changed. It would be good if the Python pundits around here could take
a look.
(I have found Python 3.0 to be very quick and easy to install from
source, in case your distribution doesn't have it packaged yet.)