In response to Dave Winer's post.
I think the short answer is "something like XMPP." XMPP has a lot of things going for it:
- It's an open standard (we can all build our own implementations and fork our own features and at a base level it will remain compatible as long as we're not dorks and break the interface).
- It's federated (I can choose who I trust, and I don't have to pay for everyone to use my server).
It needs payloads and doesn't need arbitrary length limits.
Anything successful needs to be at least as easy to use as Twitter. It also needs to have people that folks who don't care about the technology (most people) want to follow using it, exclusively if possible. That's the real challenge. The technology is easy in comparison.