About 7% of US mobile phone subscribers and 18% of smartphone subscribers used location-based "check-in" services on their phones in March 2011, according to comScore MobiLens data. In total, 16.7 million mobile subscribers, including 12.7 million smartphone subscribers (76% of the total), used location-based check-in. According to a spring 2011 study from digital marketing agency White Horse called "Lost in Geolocation", the majority of people who use location-based apps check-in several times per week. Some 19% of location-based app users check in at least 1 time per day. Geo-location app providers themselves are also reporting high levels of activity. Foursquare, one of the leading companies in this space, has reached 10 million users after experiencing a 3400% growth increase in 2010. These numbers, though, don't mean a marketer can rely on the buzz or sex appeal of geo-location — especially as the novelty of this technologies wears thin. Sharing location and aggregating messages are close to becoming commodity services - and their mere presence in a marketing campaign is not likely to push consumers to action.In a paper published in 2010 Wharton marketing professor Peter Fader warned of location-based fatigue. Get the full story at MarketingVox