MacMini Colo has a Mini take-apart posted. The "traditional" Mac Mini probably looks familiar and the new server model has another hard drive where the DVD drive used to be, but otherwise these things are pretty much unchanged.
One interesting tidbit on this: Since Apple's latest firmware updates, both the new and last generation DisplayPort Mac Minis can use 8GB of RAM (they are advertised as topping out at 4GB). However, the 4GB memory cards that are required are expensive.
