According to Digitimes, Nvidia has placed orders with UMC for it's upcoming G92/D8P GPU. This might indicate that Nvidia's normal partner, TMSC is too busy and doesn't have the capacity to make the chips for Nvidia, or that Nvidia doesn't want to put all its eggs in one basket.
The UMC factory can output some 5-6,000 12-inch wafers a month, which equates to a log of GPU's which is a good sign in terms of availability of the 8800GT graphics card which will be using the new GPU.
As this is a 65nm chip it shouldn't be too dificult to manufacture for UMC as this is a pretty standard production size of components these days.
Hopefully we can look forward to a hard launch this time with cards available from day one.