Michael Schardt (Michael S) has posted an updated version of his "Espresso" displacement painting script (now version 1.1.1). Similar in concept to SharpConstruct, Espresso is integrated into Blender with some great features.
- graphical user interface [inside Blender!]with floating panels
- 5 different tools: brush, airbrush, eraser, sponge, magnet
- 6 different shapes: freehand, line, circle, rectangle, filled circle, filled rectangle
- mirror modes: local x, y, z (also for objects without mirror modifier)
- undo / redo: preset to 16 steps - but limited by memory only
- unlimited number of strokes: constant, random, bitmap-based (bitmap-based stroke for freehand shape only)
- 5 different radial falloffs: sharp, linear, cosine, spherical, constant
- OpenGL based occlusion tests (backface- and depthtests detachable in x-ray mode)
See the thread for more info or go to Michael's site for Espresso and several other great scripts like PyTablet, an external module for adding tablet support to Blender's python scripting system, amongst others.