I have two computers, one with a HP printer on it and one with a Samsung printer on it.
Both systems have their respective pritnters listed under system-config-printer and have "enabled" "accepting jobs" and "shared" checked.
Up to a few days ago this worked fine. Suddenly I can't see either printer from the other machine and as far as I know nothing has changed other than the usual "yum update" stuff that has come in over the past few days. I can see the local printer on each computer but system-config-printer (and applications) can't see the remote printer at all.
It's odd that the remote printer has disappeared from both computers at the same time. Each computer can see its own local printer but it can't see the remote printer on the other computer.
The firewall has port 631 tcp and udp both allowed on both computers. The cups version on both computers is cups-1.3.7-26.el5_6.1 which doesn't appear to have been updated since April.