Apple apparently doesn't want you inside this thing. They decided to use 5-point "Pentalobe" security screws to attach the lower case.
For this teardown, we had to file a couple of flathead screwdrivers to take out the funky screws. We have since found the correct 5-point driver to fit it.
Here's a 1366x768 wallpaper version for the new MB Air owners out there. We won't tell where you got it from.