The beauty of evolution at its finest. From left to right: Power PC, Intel Core Duo, Intel Core 2 Duo.

Notable differences in the latest model:

An additional USB port brings the total to five, one more than the previous model (and three more than the Power PC!).

A Mini DisplayPort and mini-DVI port -- which allow for Dual-Monitor support for the first time in a Mac mini -- replace the DVI display port of the previous generation.

A Firewire 800 port replaced the old FireWire 400 port, much to the chagrin of Mac users.