For those that don't want a laptop..
Mini - small media, desktop replacement for low power requirements. Reuse your monitor, keyboard and other bits without needing to fork out a massive amount.
iMac - for those that want an all-in-one tidy desktop.
MacPro - a no holds barred workstation built for power, that's why it has two CPUs and the option for multiple GPUs (a point that will be more important going forward).
What you want is a iMac tower with replaceable parts and expansion abilities of the MP case? Support wise this becomes expensive as all the others have a set menu approach and you pay enough on the MP that it covers the extra flexibility.
