With my University Discount:
Mac Mini 1.42GHZ + Superdrive + 1Gig RAM + Wired Keyboard & Mouse = $727
I spec'ed out an AMD64 2GHZ system with the same hard disk and RAM, DVD burner, Keyboard, Mouse -- all top of the line parts, more USB ports, more Firewire Ports, Dual video outputs -- and it came in at $853, shipped. Adding Windows XP is another $92.25. I don't have benchmarks in front of me, but I'd rate the 2GHZ AMD64 as honestly 1.5 to 2 times as fast as a 1.42GHZ G5.
And I could have spec'ed cheaper parts -- Athlon XP instead of Athlon64, base motherboard instead of deluxe -- and come in well below the Mac Mini's price, still with better overall performance.
Oh, and I didn't include the $99 Applecare in the Mac Mini price, which is pretty much essential because Macs do break, and without Applecare, you might as well strip it for parts and throw it in the trash, because it's cheaper to buy a new machine than to get an old one fixed.
Just because it's the cheapest base price Macintosh, and it's small and cute, doesn't mean it's the best bang for the buck, is all I'm saying.
They are cool, but I see no sign in this announcement of Apple improving their price/performance ratio. I'm sure Mac people will shake their heads at me and say I just don't get it, but hey -- I just don't get it. It's not THAT much easier to use, or set up, it's way more expensive to fix, and it's not as expandable. It's more portable, but if you want portable, buy a laptop.