last OID and connections?

Once I get a current project to production state, I'm going to get a heap of users performing updates simultaneously through the same update.php, and that raises a few questions:

1. will pg_getlastoid() return the last oid inserted *by this user*, *on this page*, *on this connection*, or is there a possibility for them to get mixed up, because the database gets a connection from the same user (php), and reuses connections or something?

e.g. If a user changes his profile, and an administrator changes some other row at the same time?

2. I find oid's pretty clever, but are they good for unique keys? It seems, foreign key constraints won't use oid's in the current release, should i use serials instead?

thanks,
Mvh,

Johnny Jørgensen

johnny(at)halfahead(dot)dk
+45 6315 7328