the Macmini is a return to the original Imac concept as it started with the old blue CRT-Imac. A machine as cheap as a pc to get more students and other "non-power users".
To be fair, the biggest complaint I had about the original iMac is that at a price that was affordable, it forced you to use a puny 15" screen instead of letting you get whatever you want. No matter how slow a system is, I could not live without my 20" Optiquest CRT. To get more flexibility (including PCI slots), you had to pay at least a $500 price premium for a tower. The cube corrected that, but was still too pricey. Mac Mini corrects this problem completely.
I'm still not sure if I should buy one, though. I do mostly architecture-independent stuff, like Java and web interfaces. New ceramic engine headers for my Subaru would get much more use. :-)