Woodchuck has a pumpkin cider available on the market right now. I tried a bottle the other day. It was interesting, not bad, but it didn't exactly blow my sox off.
If I were to do a pumpkin cider, I think I'd add Comstock pumpkin pie filling in the secondary, along with pumpkin spice. Then let it sit for a couple weeks and rack off that into a bottling bucket.