On my recent trip I brought along my MacBook Air as my primary machine. I took care of email, administrative junk, etc. but I also did some development work. Due to its light weight it’s a great travel laptop, and one that could be shrunk further rather easily by using a screen with smaller pixels and eliminating much of the bezel around the screen and keyboard. I believe you could trim 2-3 diagonal inches off the design quite easily – perhaps a little more by going to a 95% keyboard.
With those changes, the MacBook Air would be small enough to rival the iPad in size and portability. Apple would never use the term, but it could certainly become a sub-notebook or a netbook. It’s also powerful enough that it would also make pretty much every other netbook on the market obsolete (of course, it wouldn’t exactly compete on price).
I find this interesting because I’ve been cutting back on my iPad usage of late. I still use it daily as a news (feed) reader, but I find it too limiting for doing much browsing1 or email2. Ultimately that’s why I’m not using the iPad as much – I’m just faster on Mac OS X for general computing than I am on an iOS device.
If I had a MacBook Air the size if my iPad, I think I’d probably choose to carry it as an on-the-go device instead of the iPad. Especially if the battery life was remotely similar to the iPad’s.