[eisrep]

It's no different than using Skype or Ventrilo or even a phone/conference call. There's no real way to manage who talks to who while you're playing a game.

[tetrep]

Hell, it's not different than being in the same room as other players. I've yet to hear of any games that ban teams sharing the same IP address.

[cjhopman]

Most poker games do.