And I didn't want to carry that around, so I left it at home and bought a shiny new MacBook Air SuperDrive (by 2012, Apple USB SuperDrive) for the office. To be able to continue using the SuperDrive (Apple's name for the CD/DVD read/write drive), the Optibay came with an external USB case which worked fine, but was ugly. The story is this - a while ago I replaced the built-in optical disk drive in my MacBook Pro 17' by an OptiBay (in the meantime, there are also alternatives) which allows to connect a second harddrive, or in my case, a SSD.
Note: for Mac OS X 10.11 El Capitan and later, please see this updated post instead.