Think of it as a reverse-engineered laptop with a removable screen, but one that in tablet mode is so much more than what's formerly been imagined..
Whether or not the new device runs full OSX, i see this as the start of migration of App Store Apps to Apple's larger products. And that's an exciting prospect.
You just made me realize something awesome. What if Apple re-engineered the Macbook Air so that the screen could pop off? In its docked mode, it ran at full power and ran full OS X. However, in undocked mode, the interface took all the data with it, but dropped into iPhone OS or tablet OS with a reduced set of Apps and only mobile functionality. Then you could charge $1699 for it and noone would think twice. You have a tablet and a laptop. Oh, and of course, it is also available as a stand alone unit for $999.
The only think keeping that from being true is that the Air is 13" and the tablet is supposed to be 10". Apple would never release a 10" laptop. That would be $1699 Netbook. Yikes. I'm still thinking this is going to be some form of hybrid.