It's very clever engineering in all fairness to them.
The thickest end is still thinner than one of those uber thin Vaios.
They got Intel to make them a custom version of the Core 2 Duo processor that is 60% smaller.
The entire motherboard is the length of a pencil in one direction and about a third of that in the other dimension.
What don't I like? The price due the feature set.
£1,299
13.3", 1.6GHz Core2Duo, 2GB, 80GB HDD, 1x USB port, 1x video out port, 1x audio out port.
For the same money you can get a MacBook Pro which while thicker and heavier has a 15" screen, 2.something GHz Core2Duo, 120GB HDD, firewire 400 and 800 ports, more USB ports, ethernet port, DVD burner and so on.
So if you need power you buy that.
Or for just £800 you can get a MacBook with the same size screen but extras such as firewire ports, larger hdd, faster processor and so on.
So really you're paying a £400 premium over a MacBook for the same size screen, to get the thickness and weight down, and you lose out on spec too.
So for people on a budget, the MacBook is the way to go, for power users the MacBook Pro is the way to go.
The MacBook Air then is only worth buying if you *need* the slimness and don't need the other features or much processor power.
Don't get me wrong, as a consumer machine for someone who wants to use the internet, edit digital photos (but not connect their camcorder) and who travels a lot it's awesome.