I bought an iPad for travel as I was tired of waiting for the mba to be updated and didn't want to get one and then find that a few weeks later the update came along.
However, having used the iPad for travel and done a lot of writing on it I wonder at those folks who complain about the size of the screen? Sitting on a plane for 10 hours typing away or reading books on it and there was still power in the battery at the end of the journey. Now if similar technology could be ported over to the mba whether 11.7" or 13" that would sure stop a lot of grumbling about battery power.
I reckon if one does come along it will have a uniform thickness like the new iPod touch and iPhone, there's no point in making it thinner as it would then become too fragile whatever material used, liquid metal or carbon fibre.
Nothing wrong with an 11.7" screen for travelling after all the 12" Powerbook was fine and loads of folks bemoaned it's passing.
As to memory expansion from the measly 2gb of the mba I don't understand why the same technology as used on the little Acer Aspire One can't be used? An SD slot for memory expansion and another for storage, that would solve the problem of ports on an mba. After all, SD sizes seem to be increasing all the time. That would certainly solve the problem of having to open the machine to increase memory, then we could be able to increase the memory as SD sizes increase, 4,8,16Gb ....