I actually like the way this was done on SO, any chance this can be implemented on DBA.SE as well?
We're glad you like the new navigation and want to see it here on DBA. That being said, the developers are still working on it and have a lot of bugs and feedback that they are working through which is why it's still in beta on Stack Overflow.
We're not quite ready to move it out of beta or even move it to the rest of the network. I'm not exactly sure of a timeframe for a full network rollout but I don't think it will be in the next 6-8 weeks.