Using PL/R with 8.0

I'm trying to get plr up and running on an 8.0.1
pg installation.  I'm running Debian unstable.

I have R_HOME as /usr/lib/R
libR.so is in /usr/lib/R/lib/libR.so
and has rw-r--r-- permissions.

/u/local/pgsql80/lib/plr.so is rwxr-xr-x.

I've (re)built pg --with-plr and --with-libs=/usr/lib/R/ (just in case)

I've (re)built plr.

When I load plr.sql it complains:
ERROR:  could not load library "/u/local/pgsql80/lib/plr.so": libR.so: cannot open shared object file: No such file or
directory

Please tell me that there is something stupid
and obvious that I've forgotten to set? 
(And what that thing is :)

--elein
elein@varlena.com