Fantastic idea!
I see they're competing with BlackBerry to see who can lose market share fastest and this is their trump card clearly. Nokia had an early start then HTC and BlackBerry threw their chips in but Samsung have just pulled out an incredible hand that has the potential to beat all others. After this valuable 'feature' is added I predict their next innovation will involve the phone only working with pre-approved carriers in select countries. Those networks will, of course, be the highest priced and getting some lovely little benefits from Samsung.
Region locking a phone? This really is a crazy time to be living in isn't it? Companies dodging tax all over to keep as much money as possible and at the same time using any trick they can to charge as much as they can. Burning the candle at both ends there Samsung. Great for your cash piles but not so much if you want to stay in business.