There is no way I would buy now, I'm waiting for the new models. I just sold my MBP and am currently without a laptop. I want something lighter and more portable, and don't really need "pro" power on the go. I'm waiting for an Apple laptop with current tech, because I can't personally justify the price for what is included right now. Also, 4GB RAM is a must for my use, and the newer trackpad would be nice.
The rev. A Air had Intel graphics and 1.6 or 1.8 GHz Merom CPUs and an 800MHz bus.
The rev. B moved to nVidia graphis and 1.6 or 1.86 GHz Penryn CPUs and a 1066MHz bus.
The rev. C was a CPU speed bump to 1.86 or 2.13 GHz.
For rev. D, I'd like a Core i series CPU, a more current GPU, and 4GB RAM. A buttonless trackpad, more battery life, and an IPS screen would just be icing.