It's very late, but DexCon 15 in NJ is running 10 or so slots of Shadowrun Missions.
I think It's the NAGA group that's running the games, which means the GMs will be whoever they can get that knows Shadowrun, not necessarily Shadowrun Missions experts. I'll be there as a player, not a GM.
Event site:
http://www.dexposure.com/dexcon15.htmlEvent signup:
http://warhorn.net/dexcon-12-naga/-k