A year ago I mentioned a numerical study which indicates that AdS is unstable against small perturbations.
Meanwhile, Horowitz et al. "find strong support for this idea". They also mention that "any field theory with a gravity dual must exhibit the same turbulent instability, and transfer energy from large to small scales", but it is unclear (to me) what this means for the AdS/CFT correspondence. But notice that they study AdS4, although the assumption seems to be that AdS5 contains the same instability.
Two years ago I wrote about higher order gravity models. Recently, Leonardo Modesto considered "higher derivative gravity involving an infinite number of derivative terms".
This new model "is instead ghost-free" and "finite from two loops upwards: the theory is then super-renormalizable".
Last , but not least, Daniel Coumbe and Jack Laiho have published version 2 of their paper "exploring the phase diagram of lattice quantum gravity"; a while ago I mentioned the talk about it at the Lattice 2011 conference.
added later: In a new paper Ashoke Sen calculates logarithmic corrections to the entropy of black holes which "disagree with the existing result in loop quantum gravity".