the date for the new codex for the necrons is november 5, and http://beastsofwar.com/ has pics and a breif description of some of the new models/units.
Three things intrest me, the new overlords/special characters, the new transport/tank and the new licheguard. all are beautiful, and look to have promise. it looks like they are following GW's new model of making a kit able to be made into multiple models, making for tasty additions to your bitz box.
I will post more as I hear it.