A workmate bought her macbook in for me to have a look at, turns out the rubber base is completely coming away from the main body of the macbook.

As it turns out, this is a known issue with some of the current model polycarbonate (plastic) unibody macbooks released in the past couple of years, and Apple are offering free replacements.

We lodged a claim on the website yesterday, the new base, screws and a screwdriver turned up today.

It sounds like its one of those problems that if it hasn't happened yet, it will soon if you've got one of the affected models, so, if you've bought one of these in the past couple of years, you may want to punch your serial number into the site and see if they can ship one out to you before the program ends, or you may soon find yourself with a distorted base on your laptop.

It was a "pretty big deal" apparently, but it's the first I've heard of it, so this may be of use to folks.

http://www.apple.com/support/macbook-bottomcase/

[Moderator edit (MF): hyperlinked. You can it yourselves, people]