"The hard drive is supposed to mount on the back of the Wii, and designed to look like a natural part of the console. A firmware upgrade will be required to use it. Furthermore, everything you buy from the Wii Shop Channel can be transferred unto the hard drive, no problem. The HD will be available in 32 GB and 64 GB models. "
http://www.qj.net/Rumor-double-USB-hard-drive-coming-to-the-Wii-/pg/49/aid/129397
Sounds good but hey it wouldn't be the first time they tease us this way.
Let's see what happens..