I think Gravity is better positioned to tackle the mass market. I don’t think I would feel comfortable talking about my favorite band or whether jen and brad are going to get back together on Quora, I would on Gravity. And outside the silicon valley bubble that is the kind of stuff most people talk about. You need only cast an eye over the supermarket checkout stand to confirm that this is true.

Can either site get enough users? Not sure yet. But I see the sites going after very different audiences, and my guess is the gravity market is bigger.

In the meantime, we’ve had plenty of discussion-orientated software: phpBB, Community Server, etc etc. It’s one of the few consumer segments that’s truly distributed. Will people really go back to central, cross-purpose discussion sites?