[Tunabrain]

The second version of the Kinect uses time-of-flight sensing rather than the projected grid of points, and is considerably more accurate.

Whether or not this makes the scanning more plausible, I am not sure. However, some of the 3D models generated with the Kinect 2 [1] do seem to contain a decent amount of detail.

[1] http://zugara.com/wp-content/uploads/Kinect-1-vs-Kinect-2-Vi...

[Tepix]

I have a Kinect 2 and the scans still don't come close to sub-millimeter accuracy.

There are some rumours that they scanned plaster cast instead: http://heise.de/-3117841

[TrevorJ]

Still a big issue with the artifact being behind glass. In a controlled environment where you can take all the time you need, I still don't think you could get a scan that's as good as the one released.

[joshvm]

Except the device they showed was clearly a Kinect 1.