Stross does tend towards overgeneralisation about subgenres, I've noticed, but I think he's entirely right about most steam-"punk" - the books spawned on the back of the lifestyle craze are mostly appalling (http://eithin.com/cirw/2009/07/06/jonathan-green-unnatural-history/). On the other hand, some of the trope namers (Powers, for instance) really do have interesting things to say about class.