That said, I've come to the conclusion that for a virtual team to really work the company culture really has to be on board with the idea. Particularly I think it works best when the whole team or a majority is working remotely or semi-remotely.
The two firms that I've been with so far had only one or two remote workers on an otherwise in-house team that was managed very much in the 9-5 butt-in-seat tradition. They reluctantly went with remote workers out of necessity and with management that isn't too hot on communicating other than in person and firing up a webcam is considering something worthy of planning out days in advance and reserving a conference room.
Needless to say, I'm looking for a more remote-friendly team these days, but I do think it's a good warning to anyone looking into remote work. Find out what proportion of the team is working remote, really try to access the team culture for supporting those remote workers, and do concern yourself with how much buy-in management has to the idea.