According to our Turkish colleagues at Donanimhaber.com Asus plans to release an 8800 GT with 1GB of memory. When compared to Asus's 8800 GT 512MB version it is clear that the 1GB card has a different PCB design.
According to Donanimhaber.com, clocks will remain at reference values, 600MHz for the GPU and 900MHz (1800MHz effective) for 1GB of GDDR3 memory. Since Expreview.com has a picture of the 512MB version, they managed to compare it and noticed that 1GB version will not use the referent design PCB. The PWM heatsink and the cooler are the same for both the 512MB and 1GB versions, as well as the overclocked HD 3800 series, which we wrote about here.
Apparently, the 1GB version will use a 3-phase PWM, while the 512MB version uses a 2-phase. The fan connector is moved from the top of the card back down to the bottom. The PWM heatsink has been moved a bit back, closer to the power connector, and the memory chips are placed differently. Looks like Asus made a lot of changes to fit 1GB of memory on this card.
You can find the 1GB version picture here, and the comparison can be found here.