Slated to be released in November. The person who posts "snippets" at Baen's Bar in the Honorverse forum says it will be another month or so yet before the sneak peeks begins. However, the cover art has been released (I think.)
http://www.baen.com/images/At_All_Cost.jpg
Either someone is playing a very cruel April Fool's joke, or Honor's life just got a hella lot more interesting...
And is that the Star of Grayson Nimitz is dangling there...?