A Note about rumors and sources:
Please take all rumors with a salt. Nothing is a fact until the codex is actually in our hands. I could not locate where Bigred dug this rumor up, so I listed him as the source.
From Bigred
Updated Necron Background
Necrons have now fully awakened. All previously encountered Necrons were "bugs" in the reawakening program and were under the sway of the two rogue C'tan. Now fully awakened, the Necrons are ready for their advancing story arc in the codex. That said, they are effectively "Space Tomb King" with strong parallels in both unit back story and visual appearance linking them to that Warhammer Fantasy army book.
Updated Scarabs
Fast Attack choice. Three models in base unit at 45 pts, with up to seven more at 15 pts per model. Fearless, Swarms, Beast, Entropic Strike. Fout attacks on the charge with 3+ cover save in terrain (which they ignore for movement purposes - like Harlequins) . Entropic Strike is a new rules accessable to several units in the codex. Against infantry on to-wound rolls of 4+, armor saves are ignored (Invulnerables allowed). Against vehicles on armor penetration rolls, each die that rolls a 4+, reduces the vehicle's armor by 1 pt on ALL sides for the rest of the game. Vehicles are destroyed when any of its armor values reach 0.