FT long time ago had a not so small community focused around playing via multiplayer. There were made some rulesets. The most popular are described here:
http://rules.ovh.org/
It is suggested to play by hamachi.

I played right behind with a time .... the multiplayer is quite fun ..

Interesting. I must try this out. Many thank you for beautiful thread!

The main page says something about some multiplayer modes being unavailable now. What modes are they referring to? Also, does the game have any kind of direct connection mode?
If I can play this co-op with a friend, I'm sold. If not, I'm withholding purchase for a while.

Yes. U can play by direct connection (hamachi is good for people who have their ports blocked and cant connect by ip).
If u say co-op mode, u mean playing main campaign with friend, right? I think it is possible to convert singleplayer maps to be playable in multiplayer, but it needs a bit of work. There are also some coop maps, but they need more than 2 players to be fun.
And i dont get part "some multiplayer modes being unavailable". Can u explain that? I dont see anything on main page saying that...
And also here it is movie (made by me ;) ) showing some multiplayer gameplay (rules 10k reg) http://www.youtube.com/watch?v=zYLY0ScytYo

The page for Fallout Tactics lists this caveat just above the system requirements line. It reads: "Multiplayer issue: some of the multiplayer modes originally built into Fallout Tactics game are no longer available. For details see: Support "
As for co-op, I was wondering if there are scenarios in which you and another player can work against a CPU opponent. From the sounds of things, there is no such feature, which disappoints me, as this would be a fun game to co-op. As it is, the game is too fast for me in CTB, and in either of the other modes, the game drags on forever.
I do love my Fallout, though, so some day, I'll get back to it, but it's too big to play like Final Fantasy Tactics, and it's too hectic to let go on without my constant scrutiny of every minor detail. Needless to say, I'm not a big fan of RTS. ^_^

I would be down for some MP sometime.

I guess we're going to have to wait until they can dole us out unique Software Keys, as that wasn't part of the original package. Other games have problems with multiplayer due to identical user IDs.