Here's a list of topics that I have posted on (with active links) or expect to post on (without links) related to the Desktop Window Manager in Windows Vista.

• Under the Hood of the Desktop Window Manager -- a technical introduction (and response to comments)
• DWM's use of DirectX, GPUs, and hardware acceleration (and response to comments)
• The role of the Windows Display Driver Model in the DWM (and response to comments)
• Redirecting GDI, DirectX, and WPF applications
• How underlying WPF concepts and technology are being used in the DWM 
• High DPI support (and response to comments)
• APIs in the Desktop Window Manager 
• Rendering and visibility optimizations
• Memory usage in the DWM
• Power management and battery life
• How the DWM paints the window frame and other non-client area
• Remoting, Magnification, and Accessibility under the DWM
• Best practices for applications under the DWM

If there are specific other topics you're interested in, please comment away.