As Clay Shirky recounts in "Here Comes Everybody," a woman recovered her cellphone after a friend publicly shamed the phone's thief (whose pictures and e-mail address they discovered via T-Mobile servers) on Digg.
You can also try filing a police report, on which you'll be asked to include basic information like the date, time and location of the theft and any identifying characteristics of the phone, including serial numbers (which are a good idea to record somewhere). However, unless you have a phone-tracking app installed to let you see the location of the phone, it's unlikely the police will be able to do much to help you — and even if you do know the location of the phone, the police may not be willing to devote resources to recovering it. (Pogue says that since his story went viral, he's "heard from many who could not persuade the police to act" to recover stolen phones.)
However, sometimes having filed a police report is a prerequisite for filing an insurance claim if you have cellphone insurance, which is an optional feature of many cellphone plans. Carriers can also suspend service to your stolen phone so that a thief won't be able to rack up charges using your number.
CTIA, the International Association for the Wireless Telecommunications Industry, has recently pledged to compile an industry-wide database of stolen smartphone identifying numbers that will prevent stolen phones from being reactivated on any network — effectively rendering them useless to thieves. If the database is implemented as planned in October, cellphones might become much less tempting to thieves than they are now.