I've just pulled out the connector that's soldered to the logic board because I used a pry tool. Be careful at this point to just pull gently on the four cables that go to the fan.

On my PB the screws were #7 Torx, but these may not be stock as someone before me had added a 120 GB HDD.

The aluminum upper case has a grey plastic rim that comes off with it. Running a guitar pick between the plastic rim of the upper case and the aluminum of the lower case made removal easy.

On my PBG4, I found 3 wires attached to the upper case - red and black wires that run to the power button, blue and black wires that run to the mic, and a flat orange cable that runs from the trackpad to a socket on the motherboard. The coloured wires are taped to the upper case, and don't need to be removed. The flat orange connector is directly under the square opening in the upper case, and has loop to help in removing it from the motherboard (which needs to be done). This step was not tricky at all.