On Facebook, Brandon Sanderson has indicated that it is looking unlikely that A Memory of Light will be released in 2011. He is starting the full writing process on the book in January, and given the time The Gathering Storm and Towers of Midnight have taken, it is not looking likely that the book will be out in October/November 2011, a year after Towers of Midnight, as hoped. He has asked people to keep an eye on his website around Summer 2011 to see if he can do it, but it's more likely to be Spring 2012 before the book appears.
In addition, Sanderson confirmed that he would not work on the sequel to The Way of Kings until Wheel of Time is concluded.
Sanderson has also undertaken an AIM chat with fans, a transcript of which can be found here. He muses on what characters will be back in the final two Wheel of Time books, how much research he needs to do for the project and how he does it, and rules out completing certain other in-progress fantasy series, and how he only took the Wheel job because of the impact of the series on his own writing.