Well, DX 11 GPU can be launch at any time in mid 2009 without warning. Microsoft had already gave DX 11 technical preview to video card developers like ATI and NVIDIA. This will allow ATI and NVIDIA to add DX 11 feature to their next generation video cards.
Please also note that Windows 7 beta and DirectX 11 beta were also already released. What is missing is the DX11 compatible GPU for the moment.....