Two versions of Windows.
Sometimes I think that the glitchy demonstration was designed to distract everyone from the real issues.
2012 is the 10th anniversary of Windows unification. Before that, there was Windows, Windows 95, WIndows 98 and Windows ME on the one side; and Windows for Workgroups, Windows NT, and Windows 2000 on the other side. The two tracks were only semi-compatible. NT did not have the dlls to run games, media entertainment, and other consumer apps; 98 did not have the stability to run business apps all day without crashing.
XP put a temporary end to those days. Microsoft found it wasn't easy to advance beyond XP while maintaing that unity. Vista, anyone? Many business users decided to stick with XP. Now Microsoft is going with two families of hardware WITH different processors, different peripherals, and different operating systems. In the past, Microsoft had its hands full with two operating systems on the same processor.
The MacBook Air and the iPad have different processors, peripherals, and operating systems as well; however, Apple does not try to mislead anyone into believing that the two are software compatible. I have a suspicion that anyone who believes that Windows 8 RT and PRO will be compatible will be buying a bag of hurt.