It illustrated the point with the following graph, of the power density (power usage per unit area) of current and past computer chips, with an admittedly somewhat generous extrapolation:
Somehow, I don't think we'll actually be meeting that extrapolation, rather than continuing on what they claim is the current technology path! (It's not the only extrapolation we won't be meeting; see this article from The Register on another graph in the presentation that compares Itanium sales to historical predictions.)
The worst thing is that, unfortunately, we can't use the heat for baking cookies with, either. Chips start to die at about 180F, but cookies need at least a 275F oven, and -- as Flanders and Swann point out, (cue music) Heat won't pass from a cooler to a hotter (you can try it if you'd like, but you'd far better notter)!