DirectX 11 is the next big thing in graphics. It comes with Windows 7 and the first graphics cards to support it should be available by the end of the 2009.
The launch should probably take place in the last two quarters of 2009 and the competition between Nvidia and ATI who might be the first one is on. Nvidia needs DirectX 11 more than ATI, as Nvidia decided to ship the DirectX 10.1, claiming that all the parts of DirectX 10.1 will be included in DirectX 11 spec.
DirectX 11 might be an important step in defining in-game physic as a standard, something that needs to be done by who else other than Microsoft. Nvidia will push its PhysX hard and it will be interesting to see what Microsofts plans are with this.
The first DirectX 11 games will probably be out in early 2010