Looks like Dungeon Crafter III has been out for a bit. Developer is Shard Games.

From the site:

Dungeon Crafter III has several new and exciting features, as well as many easy-to-use features of its predecessors. It is easy to create your own Floors, Objects and Walls for Dungeon Crafter III and share them with the large user community in the Dungeon Crafter III forums. Here is a list of the main features:
  • Four different drawing layers
  • 72x72 pixel Floor tiles allowing for more detail
  • Four different zoom levels
  • Alpha graphics support
  • Adjustable shadows for Walls and Objects
  • Simple intuitive inferface
  • Beautiful graphics included
-Rob A>