If you don't see your favorite platform already listed as tested
for 8.1 at
http://developer.postgresql.org/docs/postgres/supported-platforms.html
then please give it a try and send in your results.
I'd recommend using 8.1beta4 or later, as beta4 already includes a few
small portability fixes over beta3 --- no point in reinventing that
work.
regards, tom lane