FUD Zilla claims NVIDIA has successfully taped out its 28nm Kepler GPU. The expected availability date is Q4 2011 or early 2012.
We have multiple sources to confirm that the new 28nm chip is alive and that it looks quite well. Nvidia didn't have any major obstacles with the first tape out, but naturally there is still a lot of work to seal the leakage, and make the chip generally better. This is nothing unusual for a new chip, and getting from 40nm to 28nm is definitely not a walk in a park.
Kepler naturally gets a lot of changes to Nvidia's GPU and you can imagine that with the same maximal TDP, you can squeeze significantly more transistor and get much more power.