In 2009, two location-sharing services, Gowalla and Foursquare, went to battle. Today, only one remains. Gowalla had a lot going for it, including a novel concept, a focus on leveraging check-ins for event recommendation and an attractive interface. What it didn't have is as many users as Foursquare, despite launching two years earlier. Just as Facebook once struck a chord with users MySpace didn't, Gowalla found itself an also-ran to Foursquare. In December, it was announced Gowalla was sold to Facebook, a deal that culminated this month with the service going offline (although an online message suggests that users may eventually get a new interface for downloading their "passport" data). The terms of that deal have yet to be made public, although published reports have claimed that the deal does not include user data. Gowalla isn't the only location-based service acquired recently. Loopt, another pioneer in the field, was bought for $43.4 million in cash this month by Green Dot ( GDOT), a leading provider of prepaid Mastercard ( MA) and Visa ( V) cards. The deal was touted as strengthening Green Dot's push into the realm of mobile payments.