I just ordered one. $479 and free shipping for students at the Apple website.
I bought the bare bones model. It's all I need to play with, and after a few weeks I'm going to give it to my grandpa to replace his virus and spyware ridden Pentium 2. I'm not sure if I should buy a USB->PS/2 adapter so he can keep using his old keyboard and mouse or if I should spend the exact same amount of money on a new set of keys/mouse... it would be kind of neat to make the Mac Mini a complete drop-in replacement.
Mac Mini is great if all you need are "mini" features. (I'm glad it has a DVI port though). Perfect for all of those older relatives who need a machine for surfing, email, word processing, finances, and maybe some day digital photos, home movies, and dvd burning. Comes with most of the software they'd ever need. It's not for most of us power users though.