We are still actively developing Derby and Racer. We are currently working on a re-write of Racer's internals on top of ShareJS that will make Derby useable for a production app. See: http://blog.derbyjs.com/2013/03/26/getting-derby-ready-for-p...
Our initial goal in open sourcing the framework was to get some ideas out there and see what worked well and what didn't. We've learned a lot from this process, and we now have a much better idea of how to build a great system.
We are excited to see all of the innovation coming from Meteor, Firebase, and other new realtime systems. While there are similarities, our teams have different perspectives on what the future of web development looks like, and we believe there is still a great deal to be gained from further development of each of these platforms.
Currently, our changes to Racer will keep a similar API but make Derby apps much more stable and scalable to large production deployments.