I was just talking with an author of said volume yesterday. Things are on-schedule, but the schedule they are on is not yet known.
We are avoiding publishing an actual release schedule because we don't have to deal with print publishing items like pre-orders and shipping and entries into the trade magazines. Thus instead we announce when a product is nearing completion, and begin our tour of promotional work. As it stands, this particular product has not had an art call done on it yet, so obviously won't be out before June at this point.
Knowing the authors (and discussing the art call also), I'm really looking forward to getting the final manuscript in my hands.