• Facebook is working on app that tracks users' locations, a report says
• Such "social discovery" apps seek to help you meet friends -- old or new
• Privacy has been a concern that slowed growth of such apps
• Facebook also could use the reams of data to target advertising

http://www.cnn.com/2013/02/06/tech/mobile/facebook-mobile-app-privacy/index.html?hpt=te_t1