A reporter at the Verge just had a hands on with it and confirmed that you do, unfortunately, have to lift it up.

there’s no way to reach the power button, which is on the underside of the computer, without lifting it up.

Mac Mini’s are cool, and I appreciate that Apple has some of the most experienced and talented designers in the world… But they put the power switch on the bottom. You have to lift it up and turn it over to turn it on and off.