I guess that the Guild kind of already works like this, to say the truth. People drift naturally for the groups that they feel more comfortable with the whole time.

Making it an official business, would either require someone to go out of their way to make a thread, or threads, or Mahz to do more coding (which is always the last resort measure). Plus, I think that creating official Guild/teams/whatever would promote far too much rivalry between the site members as they filter into self-contained communities, which in turn would make it harder for people to experiment with ideas/groups outside of their comfort zone.

At least from where I stand, the cons outweigh the pros, for this kind of idea.