It looks like development has slowed down dramatically. In my view, a project which has a large community behind it is far preferable to something which is theoretically superior but new and small, because in the long run, long-lived projects tend to address new use cases (ie they evolve), so they don't paint you into a corner, unlike a wonderful-sounding idea whose author seemingly gets bored of it after 12 months.

Personally it is for this reason that I'm going with zeromq, even though I know it has tight-coupling downsides. I was tempted by nanomsg but even this seems to be losing momentum somewhat (please feel free to correct me if the last statement is incorrect).