Theoretically, you are right. But SMBs have heard of Foursquare and this is invaluable for them as this is how they are going to make money in the end. As for consumers - you are right for the single digit millions who check in from time to time, but for others? Foursquare is an app that was not for them, but they know it was about local and they did not mind it. The hard part is going to convince them that this new app is more interesting and better than Yelp, Sosh or others.