Ok this is a new one, using the keyboard to actually infect a system. This new type (at least new to me) can be used to take complete control of an Apple Keyboard and then a system through the use of a BIOS hack.
The hack is complete and can even keylog items entered at book time meaning it can grab encryption keys entered and of course your system password.
The attack on the keyboard takes less than 18 seconds to upload roughly 100kb of code into the keyboards firmware. The payload can be inserted thanks to a number of flaws already in existence in OSX.
The truly bad part about this is that once your keyboard is possessed you cannot simply wipe your drive to get rid of it. Doing that would still leave you open to immediate re-infection because it is the hardware that is infected.
Video courtesy of Digital Society