As some of you are no doubt aware, I'm in the process of putting together a megadungeon/setting book inspired by my ongoing Dwimmermount campaign. I have no firm release date in mind but it'll likely be in the Fall of this year. Like its predecessor project, The Cursed Chateau, it'll be compatible with any class-and-level fantasy RPG, but this time around I'm probably going to be hewing more closely to Labyrinth Lord, since it's the retro-clone that's actually closest to the way I play OD&D these days.
Anyway, I'm in the midst of getting its maps together, employing the talented Tim Hartin (proprietor of Paratime Design and the blog Gamma Rites) to produce them. The initial release will include six levels of Dwimmermount, although they'll only go four levels "deep," as there are several side levels. One of the principles I hold dear when working on Dwimmermount is that there should be multiple routes between the various levels and sub-levels. Likewise, the levels and sub-levels don't all stack neatly on top of one another but sprawl in a variety of directions. This is, in my opinion, an antidote to monotony and a key to keeping a megadungeon interesting and challenging over the course of long-term play.
Tim very helpfully created the following image, which shows how several of Dwimmermount's upper levels relate to one another.
If the first presentation of this material proves sufficiently popular to warrant it, there will be a follow-up that details the larger and more complex depths of Dwimmermount. I should note, though, that the dungeon presented in this book won't entirely be the "real" Dwimmermount, as that's an ongoing campaign and I prefer to keep its contents secret from my players. That said, the maps and their contents include many elements directly lifted from the actual Dwimmermount, for those who care about such things.