Get ready to say “bye bye!” to the Xbox 360 Memory Unit. Microsoft appears to be supporting USB drives for Xbox 360 save games and digital downloads.
Joystiq has documents and loads of photos that detail mass storage device support for the Xbox 360. Flash drive users will be able to convert a drive 1GB to 16GB into an Xbox 360 compatible device. After creating a 512MB system partition you can use the drive for a game install, profile transfer, and Xbox Live Arcade storage.
The USB storage feature has some limitations. It will not support large external hard drives since there is a 16MB cap and you can only plug in two drives. A system update in 2010, perhaps Spring 2010, will add the USB storage feature and put an end to the overpriced 512 memory unit.