This caught my eye this morning.
Looks like a sort of "Dungeon Geomorphs" type product, with maps ready made and awaiting a DM to fill with goodies, 12 interconnecting levels. I like Andy "Atom" Taylor's cover art here, which appears to depict a couple of characters somewhat reminiscent of Mordenkainen and Robilar, perhaps a hint as to the possible pedigree of the maps within?
At any rate, I love dungeon maps, so I'll doubtless be taking a close look at these. POssibly a timely release for some as well, as there's been a bit of noise in the blogosphere lately about the difficulties of megadungeon mapping. These could likely serve as a strong starting point.
There are also some related future releases, including "a treatise—an in depth essay—on dungeon-crafting in its many facets should be of interest, so we are gathering notes to add to my already 10,000+ word MS which describes the creation of Greyhawk™ Castle, Castle El Raja Key and Maure Castle™", and Dungeon Trappings, "supplemental material of various kinds, such as new magic, spells, monsters, tricks, traps and special set pieces", "this will also include primary matter gleaned from my Original Campaign files dating back to 1973, with salient art re-rendered from my illustrations done then".