While the 8800 series is the only DX10 capable GPU available on the market, it is too expensive for the mainstream consumer. NVIDIA hopes to fix this issue by developing the G84 series. It is a clocked down version of G80 with less pipes, which means the G84 will be smaller then the G80. It should be available for around $200 to $250 USD, and will be available in late March or early April 2007. ATI (AMD) will not have any mainstream DX10 parts available at that time.
Source: The Inquirer