(The obvious question is, "So why don't they just ship the computer this way?". The claimed answer is basically that the manufacturers choose a single voltage that is relatively middle-of-the-road, safe for all samples of the chip. Tuning to get the optimal voltage for each specific chip takes a fair amount of extra effort, so they don't bother.)
Neat stuff. Given that I run a machine with a relatively wimpy battery (I went for weight over battery life), there's something to be said for trying this. Not to mention the general ecological benefit of not consuming unnecessary power...