grant not working on pg_class

I've got a problem where any group or user permissions to the pg_class
table aren't being registered by either psql or the JDBC driver. I issue
the following command:

GRANT ALL ON TABLE pg_class TO GROUP apps;
-OR-
GRANT ALL ON TABLE pg_class TO sculptor;

Both apps and sculptor are valid user and group names respectively. The
command executes fine and the following query produces:
paella=> SELECT relname, relacl FROM pg_class WHERE relname='pg_class';
relname | relacl

----------+----------------------------------------------------------------------------------------------
pg_class | {=r/postgres,"group apps=arwdRxt/postgres","group
dev=w/postgres",sculptor=arwdRxt/postgres}
(1 row)

Looks good right? The permissions are there as requested. But when I try
to execute a stored procedure that, with the command below, turns off the
triggers temporarily I get ERROR: permission denied for relation
pg_class.

UPDATE "pg_class" SET "reltriggers" = 0 WHERE "relname" =
''layer_template'';

I'm using postgresql 7.4, on Mac OSX, and the JDBC driver that came witht
he source dist for darwin. I've checked the groups and it seems there was
a problem back in 6.4 or so but it was allegedly fixed. Any ideas?

Thanks,

Gregory

=====
--
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Gregory Stone | "Suppose you were an idiot, and suppose you were
guomo(at)yahoo(dot)com | a member of congress; but I repeat myself."
| - Mark Twain
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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