Botsareus has been working on DB2. You should check out the announcement forum, eg:
this thread.
I'm still making steady progress on DB3. You can check out the other threads in this subforum for various discussions. As far as a quick summary, I've got most of the major pieces in place that I need to make the physics engine work, and I'm finishing up the last few. Then I just have to combine the pieces. The graphics engine is serviceable, though it could still do with some TLC. I've got a good quarter of the work done on a fluid engine, and the DNA stuff is all worked out. There's still a lot of work to do before there's an initial release, though.
In terms of timeline, I'd like to get something I could call beta by summer 2015 at the latest. There might be some point releases before then once some of the major subsystems start coming together.