Police are using technology to capture criminals, for example by fitting out vehicles with CCTV and leaving them in vulnerable locations to lure car thieves. The CCTV images are so good that it's easy to make out the criminal's facial features and sometimes even his name and birth date tattoo'd on his neck (doh!).
But consider the question about whether such activity is ethical. From most perspectives (other than the criminals'!), it seems acceptable since the recording devices are within someone's property space which is clearly being violated by the criminals. One might argue that leaving such an attractive lure in a vulnerable place is entrapment, encouraging an otherwise law-abiding person to step over the line and break in, but what do you think? This is a good topic for a tea-time discussion in the average office.
UPDATE Oct 17th: Here's another situation with similar ethical issues. The FBI has allegedly been running DarkMarket, a carders' web exchange for stolen credit card numbers. What a great way to capture details about the criminals, the cards and the culture, but is it ethical? To make it work, they had to let a significant number of carders' transactions go ahead without interference, leading to millions of pounds worth of fraudulent purchases and costs for the card holders and/or credit card companies, banks and retailers concerned, in the same way that undercover drugs cops let and in fact help drug deals proceed until they have the opportunity to spring the trap.