It has about 0 developers on any given time, with the occassional work being done. There's been no real (fundamental) progress on it for over a decade. The issues in the hurd critique paper haven't been addressed. The L4 port failed.

Without knowing much, GNU Hurd has been in development for ages, yet is pretty far behind everything else out there in terms of usability. I think it is still active (remember a recent HN post), but it's progress is seen as being slow.