You know the drill. Episode 12 spoilers after the break.
Okay, so we know this episode is called Death in Heaven and the Missy character (aka "the Gatekeeper of the Nethersphere") has a line of dialog where she says "the dead are coming back, all shiny and new" and "within 24 hours the human race will cease to exist." We also know that there was some filming at the National Museum with an obelisk monument with what looks like Gallifreyan writing and the words, "Rest in Peace. We Promise." They're also currently spending three days filming pivotal scenes in a welsh graveyard, the same one that was used for The Angels Take Manhattan.
Well, guess what props have been broken out for this episode (All photos courtesy of Keith Evans at http://www.llanellitown.com/):
I'm not sure how the cherub fits into all this, (and the Thomas Thomas gravestone may just be an amusing coincidence rather than a prop) but there are also some rumors that the Danny Pink actor may have been seen wearing a Cyberman costume (take that with a huge grain of salt, since it seems incredibly unlikely they'd pay a guest actor to trek out on location to play a scene where his face is completely obscured by a mask, rather than simply dubbing his voice in later) and that a scene has been recorded where Clara says "don't you know who I am?" and reaches out to touch a Cyberman's face.
All of this seems a pretty good indicator that the Cybermen have found a way to convert the dead, and not just the recent dead either. Moreso, their number quite possibly includes Clara's mum, Victorian Clara, and Amy and Rory. (and maybe Danny and poor old Thomas Thomas)
Now that'll get the kiddies cowering behind the sofa for sure!