See the correction here.
According to Locus Magazine, Dangerous Women—an anthology edited by George R.R. Martin and Gardner Dozois—is now scheduled for a May 2013 release. Included in the anthology will the be fourth Dunk and Egg novella, which will follow Ser Duncan the Tall and his squire Egg to Winterfell where the “she-wolves” are said to rule as Lord Stark lays dying. A lot of fans will want to check it out when it’s published, not least to see if a certain vision of the past in A Dance with Dragons comes to fruition in the story.
Interestingly, German bookseller Olaf Keith pointed out that Amazon.de is listing a novella collection due exactly one year after Dangerous Women—May 2014. Martin has previously revealed that the first three Dunk & Egg novellas would be collected along with the fourth, in-progress novella once that was published and a certain amount of time had passed from its initial publication. It seems quite likely that one year is that certain amount of time.