This was posted to th emailing lists, but I would like to see if I can raly troops here to.
Note : I will not cross post anywhere else. 
This is just quick thoughts for what ‘CAN’ already be done. I repeat ‘CAN’.
As you know I have been trying to get somebody motivated to recreate the projection painting in blender to be faster and have a texture map painting feature. While I have been unsucessful at getting the goal. One part of hope just came alive. DectectiveT’s new Displacement feature has surfaced and is ready to destory the 3d world if used correctly 
If the displacement mapping and projection were married together it could make a chewy clay Blended drink. 
Work flow. Create base mesh model. UV unwrap. Paint on mesh in white and black values to form the low poly version of displacement grooves for the mesh. Paint in super fine details, render in Blender and the super fine details would be auto subdivided to show up in the render as a finely detailed model that looks like it took 3 million polys to create but in truth is only 1000.
Now what would be the fastest method to this would be a quick UV unwrap. My thought would be Atlas UV unwrapping, it creates a mess of uv cords. But for projection painting it would be the welcome complement to the Displacement mapping.
This is a picture of Atlas mapping
http://leigh.cgcommunity.com/site_images/dummies/part2/pt2_figureC.jpg
http://leigh.cgcommunity.com/tutorialspart2.htm
What needs to be done.
an Atlas UV unwrap algorithm. Or any quick method of getting the uv’s to unwrap quickly.
Displacement mapping to create a rudimentary preview form in the 3d view to work from.
Normal mapping.
A complete redo for speed in projection painting. And plus it is broken in 2.3
What is done.
Rudimentary projection painting.
Part one of displacement mapping.
Normal mapping math, well sort of, I talked to one coder that said that it is there in one of the texture channels. No real proof to it. Just a change of the number in the bump map tool.
Why Normal mapping? Displacement mapping takes a lot of time to compute if it is solely used for the details. While normal mapping is as fast as bump mapping, though it creates the fake bumps in all direction of x,y,z while bump only uses z. So normal mapping could be used for Super fine details and Displacement mapping could be used for the edges displacement.
What will this do for blender. Real Clay and clean modeling. Real super detailed meshes for render and game engine.
What can not be done. The amount of faces and vertices. Blender begins to stall after to many like around 3000 on an older computer. While it can now handle 200,000.
Inspiration, to make blender the best free Industry used tool. Zbrush, costs 400$ but if blender would have had these I would have never sold out 
.