One more thing...
The Macbook Air in my opinion is ahead of it's time...sort of like the iMac when they first came out. They have removed any and every space sapping, not often used feature and traded it for the slimmest, lightest, sexiest laptop with a lot of power and one of the best screens on the market. I think Apple probably had analysts that studied how a typical user uses their laptop.
Kan-O-Z
On top of all this there is the 'heft' of the MBA. Let me elaborate - I am a businessman and often would need to take my laptop into meetings. Previously, with the MBP, I would need to lug in the whole bag, unzip it, extract the laptop, put the bag away and so forth, which always looks a bit sloppy, to be honest.
The MBA is designed to slip into the hand and be held at your hip, very much in the way you would carry a folder, or a thick magazine. So you go into meetings looking much more professional, with NO bag, and the MBA always draws the odd gasp of approval (or maybe envy, don't know) as you casually flip it onto the conference table.
As to battery life, it's unlikely at a business meeting that you'll be running heavy processing apps, and anyway a meeting that lasts more than two hours is highly unusual these days.
I've also used the MBA for presentations, using Keynote of course, and though you need to have a precautionary power source connected, it's more than capable of running something of this nature, as long as you have an appropriate connector for output.
But it's the heft that is the killer part of the design. The balance is perfect when carried at your side, and, well, it just looks so much more as if you know what you're doing.
