This likely only applies to the ~2008 MacBook Pro:
Recently my MacBook Pro has been rejecting burnable media. When I put those discs into the drive, it would make some noises a few times but never even spin up, and the after a little while would just eject the disc. The computer would simply state that it was waiting for the SuperDrive. While considering booking in (yet again!) to the Genius Bar at Regent St, I read somewhere that the suggestion was the try blowing some air into drive. I can only recommend using canned air for this, but after a few blasts the drive has started recognising the discs and is burning again.