http://truepenny.livejournal.com/462238.html. And I mention it here as much because I wanted to post some useful reply about how valid I found this comparison, and realized that I couldn't coherently summarize what I meant, and yet the verbose version sounded even less reasonable.
So I figured I'd mull it over here.
As a cataloger, and especially as someone right this moment doing listings of upcoming books, having another tool to let readers know what they might expect of a title would be Really Useful. And having another way of softening the blow as I sort books into "SF", "Fantasy", "Horror" etc., would also be nice.
But, as is so well pointed out in the essay, Protean and Procrustean are ranged values, not binary. As so are even more difficult to translate into categories than the already difficult to nail down genre labels.
So, although I find the concept intriguing, I don't see any way to incorporate it into my book listings. Sigh.