At the time this thread was discussed, the unibody MacBook Pros — the model I’ve got — hadn’t been introduced yet, but I was surprised to find that the same cause applies in my case. This doesn’t fix the optical drive, although it does mean that it’s all the more critical that I get my MacBook to a Genius next Friday. It also finally gives me an explanation for the several-months-old bulge/sexual arousal and not-insignificant gap between the battery compartment door and the bottom panel of the MacBook. Until now I’d thought it was because it got pressed up against something while in my backpack in the overhead compartments during flights and therefore deformed.

And yes, once I remove the battery, the trackpad’s click is all back to its old clicky, loud self.