The official Postal 2 site is updated (thanks VE3D) with following Multiplayer Beta information:
We've been working on multiplayer, and we are going beta on Friday, Sept 12th at about 6pm PST. It won't be an open beta but we will be accepting a lot of people! For more information join irc.gamesnet.net and join #postal2beta or email email@example.com.
More articles about Postal 2
'POSTAL 2' Multiplayer Beta Announced!
by Thomas on Sept. 12, 2003 @ 7:39 a.m. PDT
Forget what you know about first person shooters, walk a week in the Postal Dude’s shoes and freely explore full 3-D open ended environments. Interact with over 100 unique NPC's. Postal 2 is all about choice; experiment with everyone and everything. And remember ...it's only as violent as you are!