Blizzard's job page is listing a position for a Lead 3D Level Designer.  Included in the description is this!

The team behind Diablo I and II is looking for a skilled lead 3D level designer with experience building levels using Maya or other similar 3D level building tools. The ideal candidate has experience creating levels in a senior or lead role on a shipped game. We would also like for this candidate to have excellent analytical understanding of competitive online play with various Blizzard Entertainment games and mods (real-time strategy, World of Warcraft, Defense of the Ancients, etc.).

The lead level designer needs to be able to create fun and interesting environments that look and play great while managing and mentoring a team of additional level designers. Skills in scripting or general 3D modeling/texturing are preferred.

Wonder what the teams from previous Diablo games may be working on?!  Blizzard hasn't said anything yet, and is likely to remain closemouthed regardless of speculation, so we'll just have to keep wondering!