A joyful story from Cambridge, where a chav burglar made the mistake of breaking into a geek house. These two tribes are not natural friends, and as the geek had previously been relieved of his possessions by an earlier visitor the place had been wired for vision. A webcam on the computer noticed motion and promptly emailed off pictures of the chav contemplating his haul: the plod were overjoyed to recognise their lawful prey, and even happier to plonk him down in front of a computer to replay his misdemeanours.
I once set up a similar system for a rather paranoid friend of mine, who was convinced that someone was rummaging through her flat when she wasn't there. She was also rather suspicious of the estate agents she was using to flog the place, and so got me to sort out some motion detection software and hook it up to an email program. We were both on the BT ADSL trial at the time, which made it all possible: the software triggered by itself from time to time, presumably as lighting conditions changed, and on dial-up that alone would have sunk the project.
It worked. There wasn't anyone making use of her gaff in her absence, but we got some great shots of the estate agent showing people around. We also had one set of him going around the flat by himself (as arranged), which culminated in him about to leave, noticing something on the computer (we reckon it was the lights on the broadband modem), and giving the webcam a cheery wave as he left. Not quite as desired.
The best way to defeat this system is to wear a balaclava, at least until you've unplugged the computer. Perhaps the problem is that they don't come in Burberry check.