No, we haven't got around to setting up some sort of a game broker institution. Then again, Steel Beasts multiplayer is ALL about coordinated team effort, so it makes sense to organize game sessions as scheduled events (like the weekly "Tank God it's Friday" TGIF sessions, or the near-daily sessions of the German community, etc.).
Typically you meet in the TeamSpeak chat room, then start the session as soon as enough players are around.
You may also want to visit the Multiplayer board at the SteelBeasts.com forum, or check out the current "Red Tide" campaign (I'm sure, additional players will be accepted at least on the Friday battles).