MBA 11".
Oops.
That machine just isn't on my radar. For me, it falls between two stools. The iPad is more handy for casual browsing at home, the MBP is better at more 'heavy duty' tasks with larger screen, better graphics, more RAM etc.
But for students, it's probably ideal. Lightweight, good battery life (both important if you're moving about all day, and may not always have access to a power point).
All the weight and girth of a laptop, none of the power. Yeah... Clamcase has what you want :
http://clamcase.com/
The iPad just isn't made for long winded typing sessions like a classroom requires.
That's quite cool, and I like the flexibility of it. I'd prefer something a little more svelte (I think I lose my man-card for using that word) and instantly detachable; ideally a clip-on keyboard which uses the iPad2's magnet points.