I've been giving it some thought lately, so it's a coincidence that you've mentioned it.

I've started incorporating a simple static-dynamic protocol that I read in Ross Enamait's article, "A Twist to Complex Training." It's punch-specific, starting off with a couple of brief holds for the beginning part of the punch and at mid-point, which is followed by a set of an explosive punch-like movement (e.g. medicine ball throws, dumb bell throws, or a barbell variation that I use).

The isometrics, I suppose is to activate more nerve pathways (or what ever it's called), and this prepares the muscles for the explosive movement that follows.

I've just read a study of how it was helpful increasing the peak force generated by a martial artist's kick: Strength Training 3 Therefor I can conclude that it would be useful for boxers as well.