According to expreview.com, Nvidia will introduce another Fermi iteration on June 1.

The card, designated GTX 460, will take on AMD's HD 5850 both in terms of price and performance. It will pack 1GB of GDDR5 memory on a 256-bit bus, but there is still no info on the possible clocks or the number of shaders.

Nvidia's planned GTS 450 is rumoured to feature 192 shaders, while the GTX 470 has 448, so the new card should fit somewhere in between, which leaves a lot of room for speculation. We can only guesstimate that it will end up around 400 mark. (416, 384, take your pick. sub.ed.)

Nvidia will let partners mess around with the design, s a lot of non-reference cards can be expected.

More here.