I was just browsing around ifixit and looking at batteries. I have a rev b (late 2008) MBA, and my biggest concern is the battery. Its got several hundread cycles on it already and coconutbattery shows its at 92% from new. Plus it only lasts 2 hours. It looks like the batteries on the rev c (2009) are higher rated and the same size/shape. I didnt see the battery in the new ones, but its rated even higher still. Im not opposed to opening up my air. Would one of these higher capacity batteries from a newer model fit and work in my older mba? Id love to see 5 hours of battery time.