Support doc: MacBook may run warm because rear vent is blocked

First Engadget reported it, and now there's an official Apple Support document explaining the issue: some MacBooks (and Pros) are apparently making it out of the factory with a thin piece of clear plastic blocking covering the rear vent. The article states the obvious: that this plastic is used to protect the notebook from dust while in the factory.

So if it looks like you're starting to get a tan from using your MacBook on your lap too often (which Apple doesn't recommend anyway), you might want to check that rear exhaust vent for any clear, plastic blockage.