Nvidia Sources claim that the GPU manufacturer is making a dual chip graphic card based on the GF104 chip which is the successor of Fermi. It will get lower TDP's and better performance per watt.

It will surely take the crown from ATI for being the fastest card as it's alway's good to win and have the fastest card on the market in terms of performance.

The GF104 chipset on which the GTX 460 card is based will have lower TDP then Fermi and users can achieve higher clock and overlclocks with the similar TDP's of Fermi and it'll be as successful as the G92 chip 8800gt as Nvidia was referring to. Ati while on the other hand aint working on any Dual chip based card but should be working on their reportedly next generation 40nm based products.

So far there has been no launch date confirmed about the dual chip based cards and no specs are available.

Source