According to Treyarch community manager J.D. (a.k.a. JD_2020 on the Treyarch forums), the patch is "in test right now, and is looking great." For those of you who remained spitefully out of the loop on the map bundle, it includes three standard levels -- Bonsai, Corrosion and Sub Pens -- and a swampy, undead-plagued stage called "Shi No Numa," which we believe is Japanese for "Oh crap, Zombies."
[Via Evil Avatar]