testing plpython3u on 9.0beta3

I'm testing beta 3 and ran across a PL/Python3u bug again.
This time it won't let me install it at all.
Kubuntu 10.04

./configure --with-pgport=5433 --with-python --with-ossp-uuid --with-libxml
--with-libxslt --with-perl --prefix=/usr/local/pgsqlb3
make
make check
sudo make install
All work fine.

However....
postgres(at)cspotts-laptop:/usr/local/pgsql/lib$ createlang plpython3u
ERROR: could not access file "$libdir/plpython3": No such file or directory
STATEMENT: CREATE LANGUAGE "plpython3u";

createlang: language installation failed: ERROR: could not access file
"$libdir/plpython3": No such file or directory

Thoughts? Ideas? Am I doing something wrong? If I can provide more detail
about something specific, let me know.

--
Chris Spotts
rfusca(at)gmail(dot)com