Bob and Joe, who rock at defense, go in channel 2, the D channel. Dick and Harry are the main capture gods, so they go in channel 1. In game, you can select which channels are able to hear what you say, and which channels you can hear. That way the defense guys can concentrate on the base defense strategy stuff without tying up the airwaves for the offense guys who are trying to co-ordinate a pincer attack. In theory, that's how it's supposed to work.
Reality is a bit different.
Since I'm not in a clan, I don't have a regular group of people to play with. I scoured GameSpy Arcade and MSN gaming zone looking for people who also had a GV that I could team up with. We couldn't connect to each other, but this may have been some wacky DSL problem. I never did find anyone. The casual gamer might be pretty frustrated by the lack of options out there.