Martin is skipping Comicon and other Fantasy convention to work on book. I have seen articles about the book now possibly coming out this year. However it seems like the source is just Martin denying that the publisher said about it not coming out this year.
http://www.idigitaltimes.com/winds-w...aratoga-423360
He did say this, fwiw.... In Martin's "Not a Blog," he stated, "Should I complete and deliver 'The Winds of Winter' before these cons roll round, I reserve the right to change my mind."