Premature optimization is actually cool.

People stress out about random number generators too much.

Perhaps he did found a new bug in TeX and announce a new version?

It is rare enough to be called 'Earthshaking' but the probability is really thin.

I guess something TeX related, since it's at the TeX Users Group anniversary.

I'm not sure that's the best guess. While it would be the obvious choice, I don't think much could be said to be "earthshaking" there, and Knuth isn't one to throw out hyperboles. I think it will be something new, almost certainly in a different field, and it will involve looking at an unsolved problem in a way different than it's previously been approached from, much like TeX. I can't wait to see what he announces.

But then, it is not announced as an earthshaking announcement, but as an "earthshaking announcement." The quotes make it sufficiently vague that it could be anything from "there was a typo in a comment in the metafont source", to "Vol. 4 is off to the printer."

Vol 4 is off to the printer. He's already announced that the first 5 fascicles will be appearing in hardcover later this year.

I'm willing to bet that it is not. The words are in quote marks which suggests nothing majority earth shattering (on the wider stage).

Probably a big TeX thing, given the context.

It's titled "A Special Announcement!" in the TUG conference proceeding. I'd say the odds are pretty good that it's TeX-related.

P=NP

Clearly this would be an exciting announcement, but is Knuth even known to be working on the problem?

Only in his sleep.

Isn't every computer scientist supposed to work on P=NP in their sleep? Or maybe it's their lack of sleep.

I forget who it was that said it first, but one of my profs relayed it as serious advice: that every computer scientist should dable in P=NP in his early years, then go off and do something useful for a few decades, and come back to it to dable again.

He's solved the traveling salesman problem in Log(n) time.

"Pepsi tastes better than Coke"

That would be earth shattering because it is so not true.

He's figured out the optimum way to burn all his pirated mp3s to DVD.

A solution for the iPhone antenna problem.