This is getting more than interesting. Out of the new entrants, I have to give the edge to Facebook. Assuming all of these companies can put together sales fo

This is getting more than interesting. Out of the new entrants, I have to give the edge to Facebook. Assuming all of these companies can put together sales forces capable of finding good deals and vendors--but getting a corps of 2,000, like Groupon's, can't be all that easy--the whole revenue equation boils down to subscribers. More subs = more sales. The edge there has to go to Facebook, who, I would expect, will be able to weave something quite clever into their UI to allow and encourage people to shoot these deals out to their entire friend network. Their subs list could get massive quickly.