Hi Christian,
Most rendering engines are slowly moving towards adding some stereoscopic support (AMD QB Stereo or Windows 8 Stereo). AMD QB stereo unfortunately only works for full screen exclusive applications only. There are no plans as such for adding windowed mode support since most 3D applications using stereoscopic rendering are full screen applications anyway. There are however middleware alternatives (TriDef) that provide stereoscopic support for several AAA titles that do not have native support. Unfortunately, TriDef uses Quad Buffer stereo extension and does not support windowed stereo.
Thanks,
Rohan
(Senior Graphics Engineer)
AMD D3D Driver Team