Even though a don’t agree with many of the decisions and laws created in Venezuela, I think this is great example of implementing a control for a big risk.
The Venezuelan telecommunications regulator Conatel, decided that operators have to implement mechanisms to block a mobile phone once reported stolen by its owner. This blacklist, so to speak, should work between the three main operators in the country and they even got RIM (the maker of the Blackberry devices) to agree on blocking these devices world wide.
Here is a link to the story in Spanish.
I remember from when I wrote my thesis back in 2003, that this feature is part of the original design of the GSM system, so these black lists could also be implemented at a worldwide scale. I also have information from a colleague from Romania that this system has been effectively implemented there and has reduced the theft rates dramatically.
So coming back to controlling risks; this measure if implemented correctly should reduce the risk of having a mobile phone stolen because it cannot be sold. The real impact should be seen in a couple of months once enough phones are effectively blocked and the repair shops have enough spare parts (I have no doubts that many stolen phones will be chopped up).
Update 22/01/2012: after a recent visit to Caracas I checked up on this issue. Seams like the actual bureaucratic burden does not let this policy to be correctly be implemented. I hope this gets better with time.