For better or worse, most development discussion happens on GitHub rather than julia-dev. I've been catching up on GitHub threads recently, and the progress towards 0.5 is really impressive -- both in the language itself, and in the tooling (especially the debugger). I think the nature of priorities has changed somewhat as the language matures, but I disagree that development has slowed. (disclosure: I'm a Julia committer, but have been a bit out of the loop for some months now)

There is certainly a need for better interim communication on progress between releases, to let people know what is happening without reading every GitHub thread.