According to multiple sources, it seems that the new NVIDIA 28nm chip with the codename of Kepler is being taped out. Tape-out means that it is the final design cycle for integrated circuits.
So at the moment it does not seem that NVIDIA has any problems or issues with this chip so far, but it is still in the testing phase.
They are making a transition from their Fermi chips which were at 40nm to 28nm – I doubt that is easy! But this new chip will be able to pack a lot more transistors than its predecessor, Fermi.
If we are optimistic, we might be able to see NVIDIA push out some Kepler chips around Q4 2011, but that would be very optimistic because TSMC needs some more time to be able to make these chips properly.
Though as it seems there is a slight chance that we can see Kepler in Q4 and mass availability in 2012, but we are not 100%.
AMD/ATI is also working on their 28nm part, and I will try to gather information about this as well.
So stay tuned!