Last fall, six computers were stolen from Workspace Cafe in Gastown, a popular Vancouver coworking space that hosts numerous community events. With nothing to go on except a low-res security cam video, it looked like the computers were lost, until an unexpected picture was uploaded to Workspace Flickr account. One of the iMacs was set up as a kiosk where folks could take pictures and upload them directly to Flickr. This picture quickly made the rounds on the web, hitting the top of Digg and getting covered by mainstream media. The man in the photo turns himself in (he was supposedly the second hand buyer, not the original thief) and the iMac is recovered.
If this sounds like a fun way to foil theft, you might be interested in MacTrak, from Portland-based GadgetTrak. MacTrak uses any Mac's iSight to take a picture every 30 minutes and upload it to Flickr (you can set these photos to private by default). It also uses WiFi-based location finding to attach the location to that photo. If a thief connects to the Internet at all, their picture and location will be revealed immediately. GadgetTrak also makes theft recovery and remote data wipe software for Windows PCs and mobile devices.