RobJk, here's a description of what a team is/was from the 2004 GUI Champs, the 2008 should be similar:
You will be able to enter skins individually or as part of a team. The top teams
will get a big bonus prize. Anyone can form a team and there are no restrictions
on the size of team (though obviously the bigger the team, the bigger the split
in the prize money). You could have a Team MyfavoriteWebsite or a Team "l33t".
It's up to whoever starts the team (on Monday there will be a mechanism on
www.guiolympics.com to create your own team).