When I meet people in hackathons like these, I follow them on Twitter for their technical views. But, they tweet about things that I am not interested in - like "their dog pooped today morning". Why should we follow all views of a person? This makes our timelines noisy; filled with irrelevant information. Why can’t we follow only certain persona of a person that is relevant to me? That's idea behind Persona.
Persona allows users to express themselves in 3 different personas (Techie, Democrat etc). We can then follow the persona that is relevant to us and keep our timelines clean. This is built on top of Twitter using machine learning.