It looks as though Foursquare has followed Twitter and Facebook and now has promoted ads within the application. The ads appear with a local business nearby with special offers, also showing who of your friends has been there.
These ads don’t seem to be causing any upset and they are not really in you face in the application. They only appear when you click on the “Explore” option, which is really a pretty nice feature. Now merchants and business owners are able to send local updates, or specials, and also pictures as well so that Foursquare will promote them to people nearby. For the time being the “Promoted Updates” are only rolling out to large chains such as Gap, Old Navy, Hilton, JC Penney, Best Buy and Walgreens.
Mark Cathey's Tech Site 