The BBC website has brief synopses of Series 6 Part 2, alongside a reasonably interesting long trailer.
They also released a teaser trailer of a skeleton (presumably the Doctor's) holding a dying sonic screwdriver.
You know, from the BBC's S6P2 trailer, I now have a fledgling theory that Madame Kovarian is somehow River Song. Even knowing how River dies (or rather, lives), there's any number of plot devices Moffat could pull to achieve this, although I doubt it'll be the eventual case.