The engine is open source, its only the surface of Keet that isn't for the time being (not sure if they have a date right now, but it will be with the final release). They are also releasing an entirely open source "Pear Runtime" which will be a simplified platform to build any app or service on top of without any infrastructure costs at all. The point is to make it possible to build a competing version of Keet, basically in a few hours.