It's not looking good for those wishing to purchase the GT300. The huge die (23mm x 23mm! ) and low yields from the 40nm manufacturing process are going to make the cards mighty expensive (about 1.5 times more expensive than the GT200). http://www.nordichardware.com/news,9749.html
Nvidia's fatal mistake apparently. They always insist on those huge dies... G80 and GT200 were prime examples.
But bigger is ALWAYS better. Just wait for the GT version which will be cheaper, smaller die and better than teh GTX version... just like the 8800 series Oh, and the GPU will be smaller so it fits in cases.