(Agree with most of your points) Yahoo and Google have both posted things before to the effect of "web authors: it'd really help us out if you did X", and ofte

(Agree with most of your points) Yahoo and Google have both posted things before to the effect of "web authors: it'd really help us out if you did X", and often times the other will adopt the convention. The spec only describes some uses of link elements for example, so it doesn't really seem like an abuse of anything as much as it is a case of saying that something which was previously undefined now means something to you (or them).