Dalton Caldwell is refocusing App.net into a realtime feed platform, which he proposed in What Twitter Could Have Been:
I believe so deeply in the importance of having a financially sustainable realtime feed API & service that I am going to refocus App.net to become exactly that. I have the experience, vision, infrastructure and team to do it. Additionally, we already have much of this built: a polished native iOS app, a robust technical infrastructure currently capable of handing ~200MM API calls per day with no code changes, and a developer-facing API provisioning, documentation and analytics system. This isn’t vaporware.
To manifest this grand vision, we are officially launching a Kickstarter-esque campaign. We will only accept money for this financially sustainable, ad-free...