The Media Mini would most likely be shaped like most DVD players or other A/V hardware components. It would also work as a Airport Express and be able to link to other Macs wirelessly.
Here's my rendition: (a better name would be the Media Mini or something like that, but The Mac is what got on the picture)
It features an iPod like interface built into the front so you can play music without turning the Mac on. It supports Front Row via a remote.
Supports up to a Terabyte of storage for DVR functionality with hot swapping HDDs