Looks interesting and I would certainly buy a Macbook air with Osx Lion but as always with Apple, it's tremendously overrated. The issue here is that they take advantage of Microsoft's slowness in innovation and product release cycles. If you think for a minute, MS has been late to the game in last 10+ years (e.g., Windows Phone 7, Windows 7).
Apple has Osx Lion, Google has ChromeOS, Microsoft will have Windows 8 in 2012. Windows 8 looks promising but I have some doubts about that hybrid shell and windows traditional desktop. Yes, Apple also keeps the same traditional desktop but it has improved some features in the OS and also mouse gestures.