(As with most leaked information, don't take any of these specs for granted). According to the site 3DCenter.de, Nvidia's NV40 will use 175 million transistors developed at 130 nm with an 8x2 architecture capable of doing 16 passes without rendering Z values.
The chip is still DX 9.0 with PS 3.0 functionality but has more efficient shaders then NV38. It will support DDR 1 GDDR2 and GDDR3 memory and will work as an AGP 8X part, with the chip clocked from 500 to 600MHz and memory at 600 to 800 MHz. Nvidia will announce it at either GDC or CeBIT - with market availability in April/May. The site reckons the name will be the GeForce FX 6XXX.
Read more: The Inquirer.