Unprivileged access to pgsql functions?

Good afternoon.

I've been looking at the Oracle Functionality package. It's very
interesting. However, the one place I'm stuck is that while user Postgres
can access the functions, no other user seems to have access. I'm sure this
is something simple I'm missing, but so far Google hasn't shown me the
answer.

I've already tried explicitly granting execute permissions on the function,
and the search path, as I understand it, is already supposed to be looking
in pg_catalog.

Any pointers?

**** Non-privileged user*
offload=> select nvl(null,1);
ERROR: function nvl(unknown, integer) does not exist
LINE 1: select nvl(null,1);
^
HINT: No function matches the given name and argument types. You might need
to add explicit type casts.
offload=> \q
-bash-3.00$

**** Postgres user*
-bash-3.00$ psql
psql (9.0.3)
Type "help" for help.

postgres=# select nvl(null,1);
nvl
-----
1
(1 row)

postgres=# \q

TIA,

Matt