I agree they don't seem to be innovating, but heck, neither is craigslist, and I don't see them going anywhere. I think that until someone else would need to come along with something significantly better /and/ have significant advertising dollars to compete with ebay. (either that or ebay would need to screw up it's reputation system and badly.) I don't think that facebook or any of the other social networks will compete in that arena... the social networks may help in advertising, e.g. driving people to a particular purchase, but I go to ebay to /find/ something, and I don't think facebook is a useful model for that sort of thing.

Sure, you can buy shit from your friends on facebook; I do that without an online social network, through mailing lists and other informal networks. But I don't think that really competes with ebay in any meaningful way.