Don't worry about the battery. This time it can be swapped with just a Phillips screwdriver, in 20 seconds.
This is good news, indeed, but I still have the same issue as NW_Mike - last time I tried (by mistake) to take a Phillips screwdriver on a 'plane, the earnest young chap at the security desk took it off me. Along with some expensive precision pliers. (Never did get them back, despite assurances that they'd be in lost property to collect when I got back - mysteriously vanished, presumably into the security dude's pocket.) Bizarrely, they have no problem with taking, say, a sharp, steel barrelled propelling pencil onboard, so if you really want to stab people, go for one of those. Maybe they're afraid you'll dismantle the aircraft with a small screwdriver? Or your Macbook? But I digress...
I guess the "changing battery in mid flight" issue only applies to us skinflints who travel steerage - business class seats have power available. So it's arguably down to target audience again. I'm sure they'll sell enough of them. Me, I'll go for an ultra-portable for The Rest Of Us (TM)

(and wait for the next gen one in hopes it has more ports and more advantages).
Given the premium price of the Air, justified by its being ultra-portable and very slick and cute, I really don't see why Apple haven't included at least one other USB port and a mini firewire port - even a FW400/iLink would make perfect sense, since then you could use target disc mode etc. and stream video from the ultra-compact hard-disc HD video camcorder (which you doubtless have if you're in the "must have a shiny new gadget" section of the market). Even my partner's plaything eeepc seems somehow more useable, the more I think about it - that has 3 USB ports and an ethernet port, weighs a pound less, can be used in a cramped airline seat, can be fitted with an internal modem, has a quick-swappable battery and only costs 200 quid, so it's not such a disaster if someone nicks it. (Also, you can't get so many confidential government records on its 4G drive... though it's possible, with screwdriver and soldering iron, to fit 32G of SSD inside an eeepc (along with bluetooth & GPS) for a hell of a lot less than an extra grand.)
I like my titanium G4. I like my MacBook. Won't be buying an Air, though, not even if a sudden spare couple of grand comes my way. It's just not small enough to justify the price and compromises. More or less the same footprint as my MacBook, and I'd save what, the thickness and weight of a glossy magazine, but I'd lose all the ports, the swappable battery, the decent sized hard drive and probably also the robustness (I don't trust aluminium cases not to dent or bend). And it would cost me a load more. The Air doesn't have
enough "wow" even to be desirable just for the bling, to my mind. Make it a quarter inch thick all over, a bit smaller footprint and give it a deep-colour 1920x1200 display, then I'd say they could leave off all the ports and charge twice as much and I'd still want one. But as-is, so what? It's a PDA in a huge case with a glowing apple on it.
On the plus side, good to hear they've improved the screen over the MacBook - the glossy-screened MacBook is a recent low in Mac laptop screen quality. I know it's their "cheap" option, but I didn't expect the same LCD panel as a 400 quid Acer. (I much prefer my TiBook for visual stuff, although the MacBook leaves it for dead performance-wise.)