There's a thread at POTN in regards to the lens. People seem to be warm to the idea of it. I am too. Not going to 200 would probably allow the lens to be a bit faster and sharper. It also wouldn't impede on possible 70-300 IS sales as the overlap is far less.
I'd assume such a lens would replace the not so great 17-85 and appease the crowd demanding an 18-200.