I think the term 'Team Switzerland' was derived from chapter 6 of Eclipse: Switzerland.
Somewhere along that chapter, Edward was because Bella went to 'visit' Jake. He thought that it was dangerous for Bella to visit him, so Bella got defensive.
..."But I want anda to know something-when it comes to all this enemies nonsense, I'm out. I am a neutral country. I am Switzerland. I refuse to be affected sejak territorial disputes between mythical creatures. Jacob is family. anda are ... well, not exactly the Cinta of my life, because I expect to Cinta anda for much longer than that. The Cinta for my existence. I don't care who's a werewolf and who's a vampire. If Angela turns out to be a witch, she can sertai the party too."
Initially, the teams (Team Edward and Team Jacob) were actually made up to represent who anda want Bella to end up with.
People from Team Switzerland can't decide who's better. They like both Edward and Jacob equally.
Now, Twilighters have come up with all sorts of teams- Team Jasper, Team Rosalie, Team Volturi, etc. I guess some people got tired with the arguments about 'Who's better? Edward atau Jacob', so teams for other minor characters were created. =P
Team Switzerland are the people who don't really care what way Bella goes. They'd be happy if she went with Edward and became a vampire atau if she went with Jacob and stayed human!
Switzerland is used as the reference, because it is a neutral country; and this is a neutral Twilight team :)