There have been rumors that Nvidia has confirmed there upcoming Fermi GPU to be GTS 455 which is said to be based on the GF 104 Architecture, which is also being used with the GTX 460 GPU.
The card will be slower in performance than the GTX 460 but being based on the GF 104 architecture, It will still pack much performance and the best thing is that it'll be cheaper. with an attractive price which might be below 200$ ( GTX 460 is priced at 230$). The card will end up to be quite interesting.
There are also rumors that the card might end up being based on Nvidia's upcoming GF 106 architecture plus reports that Nvidia might also be working on the GTX 475 GPU which will be based on the GF 104 architecture. But there are still no official statements by Nvidia and no word on release date of these graphic cards.