Click to download PDFI've put together a PDF file that details my setup for mapping Photoshop CS5 functionality to the Wacom Intuos4 control surface. The settings primarily focus on maximizing control of the Mixer Brush, as well as shortcuts for Photoshop's color selection tools.
For example, you can use the pen's barrel buttons to switch the Mixer Brush between opaque and blender behavior, as well as load your brush with multiple colors. You can set up the ExpressKeys to display the HUD Color Picker with a single button press. You can set up the Touch Ring to scroll back and forth through history—hey, let's go back to the future!
You may not want to use all of my settings, but they will act as a good starting point to evolve your own preferred workspace. You can download my CS5/Intuos4 PDF using the link below: