Mozilla tends to announce projects when they begin so people can contribute to them right away. I think that's a good thing and that's one of the reasons I work for Mozilla.

By the way, I think this is an awesome effort by Josh and the others working on this. I work mainly in security and networking, and I'm excited about anything we can do to make end-to-end communication more efficient because these kinds of improvements help enable more use of HTTPS and help reduce (hopefully eliminate) the need for content transforming proxies.