An example of making the smart object useless comes from a post by Ed Felten talking about how DRM can be used for good, to help prevent your stuff from being stolen.
How might this work? One possibility is that when the device [iPod] is plugged in to a charger it hasn’t seen before, it makes a noise and prompts the user to enter a password on the iPod’s screen. If the correct password is entered, the device will allow itself to be recharged by that charger in the future. The device will become associated with a group of chargers over time.
There are obvious holes with this approach, most notably stealing the charger, but it seems to me a generally good idea.
An example of making it easier to find the thief is FlickrBooth, which uploads pictures taken from a Mac's iSight camera to Flickr. There's already been one well-publicized example of successfully catching a thief.
A variant I'd like to see: something that can fingerprint the output media of cameras, so if anyone uploads a picture from that camera, you can find it. For example, Flickr already posts a lot of metadata about the camera that took the picture. So somehow record your camera's metadata in a "safe" place, and then use that to search for it if it ever gets stolen. Another possibility: I'm sure some cameras also have unique characteristics. The one I had that was stolen had a subtle scratch mark on all photos. It would be nice to be able to scan lots of images and find if anyone is publishing photos with it.