According to Andy Beal:

The way Edgeio works is that bloggers would post items they want to sell right on their blogs, tagging them with the word "listing" (and eventually other descriptive tags). Then, Edgeio will pluck them as it constantly crawls millions of blogs looking for the "listing" tag and index them on Edgeio.com

I'm impressed. I didn't think there was room in this space for another player, but this actually has the potential to take off in my view. Just goes to show that you can play in a crowded space as long as you get creative. Edgeio's in private beta now, but I'll keep an eye on them.