The Raspberry Pi Zero is a new version that lowers the cost of gigahertz-class computing devices to just $5. It is based on a 1.0 GHz ARM11 core from Broadcom that is about 40% faster than the original Raspberry Pi. It also has 512MB of RAM, which is a lot for embedded or hobbyist applications. In fact, it doubles the original Raspberry Pi Model A (and is on part with the Model B). Storage is handled by a microSD card slot, as is the case with every previous Raspberry Pi except the Compute Module.
They also offer an alternative to the $5 price tag. If you pick up the print edition of MagPi magazine #40, which is the Christmas 2015 issue, you will receive a free Raspberry Pi Zero. The Raspberry Pi Foundation says that they printed 10,000 copies of this magazine. This is probably much more interesting than a CD-ROM demo of Battlezone II.
Due to high demand, I'm not sure when you can expect to get one though.