Back in the early WOL days, games were only allowed for up to 2 vs 2. Once the 8 player patch was created we could play up to 4 vs 4 clan games (and have the WOL ladder accept the points changes). I think most people would be in agreement that support up to 4 vs 4 would be beneficial to the CLAN ladder environment. A 4 vs 4 clan battle on forest fires, now that we can (easily) choose our spots and allies before game would probably be pretty epic.
Edit: When clans and ladder are released, is there going to end up being email and password validation on accounts that want to participate? I assume you have put thought into preventing people from changing their name to another persons and losing on purpose.