Yeah, I have a copy of Superheroes somewhere, and I enjoyed it very much. Two stories especially spring to mind: "Peer Review" and "Reflected Glory" -- I think, but am not sure (I haven't got the book to hand) that the latter was written by Kurt Busiek.
Paul Kupperberg, actually.
I've never read SUPERHEROES, though at least two of the stories in it were originally submitted to a never-published superhero prose anthology I was co-editing at the time.
EDIT: D'oh! And now I see that the correction was pointed out sometime back. That'll teach me to navigate the board by searching on my own name...
kdb