Ever increasing OIDs - gonna run out soon?

Back in April 2006 I emailed about high OIDs in a 7.4.6 database.

I've just added new tables to the database (and the slony-relication
set) and I'm seeing much higher OID values for the new tables.

In April I added a table, it was assigned an OID value of 94198669 (94
million). I've just added three new tables (using an interactive psql
session), and the OIDs assigned are (now in the 182 million range):

wcpartner          182027615
wccustomdata       182027995
wccustpartnerdata  182028076

All the tables are created without OIDs, eg

create table customer.wcpartner (
   wcpartnerid        integer,
   name               varchar(32),
   wduserid           integer,
   primary key(wcpartnerid)
) without oids;

And the three tables were created in the same session within about 1
minute of each other.

By way of comparison, the oids for the Slony slave (7.4.11) are

wcpartner            38220869
wccustomdata         38221080
wccustpartnerdata    38221139

This is a normal production database with slony replication 1.1.5 and is
mainly accessed from a web application using JDBC.

I don't use any temporary tables - so what can be using up all the OIDs
(especially between two successive create table statements)?

It looks like the db is using them at the rate of 1.5 million per day.
At what value will I hit a wraparound, and what options do I have to
identify/fix the (impending) problem.

Thanks.

John