Yes, the RT ARM based devices such as surface can be locked because, well nothing but Metro Apps will run on the RT tablets anyway. I suspect there is no legacy desktop on the Surface, because it would be useless, it only makes sense on the intel version.
Speaking of which, anyone care to guess what percentage of early Surface buyers realise they can't actually run anything but (the currently 200+) metro apps? That they'll never be able to run those old Windows programs? My guess is it's less than half, judging by the fud that's out there right now....