Direct2D

Direct2D can be used on Session 0 !!
http://blogs.msdn.com/b/directx/archive/2009/09/11/using-direct2d-for-server-side-rendering.aspx

but only with software rendering :(
http://en.wikipedia.org/wiki/Direct2D

Direct2D can minimize CPU usage and utilise hardware rendering on a graphics card that supports Direct3D 10.1 and/or Direct3D 10 Feature Level 9 with WDDM 1.1 drivers, falling back to software rendering using WARP10 in situations when hardware is not available, such as session 0, and for remote server-side rendering. Direct2D performance and memory usage scale linearly with primitive counts in both software and hardware.

Direct2D vs. GDI

http://blogs.msdn.com/directx/archive/2009/09/29/comparing-direct2d-and-gdi.aspx

Surface sharing among various technologies

http://msdn.microsoft.com/en-us/library/ee913554(VS.85).aspx

Example on how to draw bitmap using Direct2D

http://msdn.microsoft.com/en-us/library/dd799443(v=VS.85).aspx

Writing DPI aware application

http://go.microsoft.com/fwlink/?LinkID=129588