I believe both the Inq and Fudzilla claim nVidia will have 55nm shrink of GTX260 and a GTX260 X2 near end of the year or early 2009.
Other than that, we'll be waiting for what AMD and nVidia have to offer with their 40nm process shrink in late Q1 or Q2 2009. Going one (AMD) to 1 1/2 (nVidia) nodes down in size should offer both companies a lot of opportunity to improve performance, cost, and power.
There is also speculation that both companies will offer even more efficient/integrated X2 GPU cards, delivering better SLI/CrossFire in a card performance scaling.
Seems like we have all been reading the same rumors and projections.