iPhone 'kill switch' does it exist?

I don't mean the Kill Switch app currently offered by HubApps which is just a force quit application.

I mean an actual kill switch that will shut down the phone and make it inoperable in case it is stolen.

There is a lot of debate in the media over this right now. A NYTimes article on Sunday says that it is available, but I can't find it.

Does it really exist?