Well apparantly Gav has parted ways with GW. No idea right now for the reasons behind it but Brimstone on Warseer has confirmed it:
People do move on, no matter how much GW or members of this forum would like them to stay.
Second yes Gav is leaving GW, he's put in a hell of a contribution both to Games Workshop and Warseer and I'm going to miss him.
I'm pretty sure Alessio is not leaving however.