The expense notwithstanding, programs like GadgetTrak do result in equipment recovery now and again. The creators’ blog explains how it works with a splendid real-world example:

The system was stolen two weeks ago and then connected to the Internet two days ago, the device was recovered this morning. GadgetTrak’s MacTrak software captured a photo of who was using the system as well as pinpointed the location within a few meters, all of the data was uploaded automatically to the device owner’s Flickr account and email. The NYPD followed up and recovered the system, along with two other stolen laptops from different cases.

Smart thieves reformat, but most thieves are not smart.

GadgetTrak Recovers Stolen iMac In New York [GadgetTrak via Gadget Lab]