http://www.semiaccurate.com/2009/07/...300-tapes-out/

Our sources tell us that the GT300 is beginning it's 7 or 8 week long process through the very expensive machinery at TSMC. We said the target was a mid-July tapeout, and if you are very charitable with 'mid-', Nvidia hit it. A hair under a week ago, the chip had not taped out.

...if everything goes perfectly, not so much as a hiccup, we are looking at mid-December for the first syphilitic trickle of parts.

The chances of this happening are somewhere around zero though. Nvidia can't make GT215s in volume, and that chip is about 1/4 the size of GT300. Toss in that this is going to be their first GDDR5 part, their first DX11 part, and their first part on a new and untested architecture, and you are likely to have at least two spins.

Each spin is the same 8 weeks as the last hot lot. Adding one puts production silicon out of the door, with the previously alluded to trickle, in late February. A second spin puts it into Q2. If there is anything more, well mid-year is very likely. Smart money is on at least two spins.
so nvidia should have early ES cards in 4-8 weeks from now, which means september-october. if those work alright (very unlikely) we might see some performance previews which would be very interesting!

they will most likely need at least 1 respin, and each respin is 6-8 weeks, so best best best case scenario:

a0 silicon works perfect or good enough and comes back in september already, nvidia sends out ES silicon as review cards in september, immediatly kicks off mass production, 10 weeks later in mid november we have mass production gt300 cards.

both nvidia and tsmc have seen better days execution wise, quite some good engineers left nvidia and were bought by intel and its pretty likely that we wont see a best case scenario... having gt300 by christmas is very unlikely, and mid december is pretty much too late to hit the holiday shopping race, from there on its holidays until 2010, and in asia even 2-3 more weeks holidays after that...

id say realistically the earliest we could see gt300 is in mid january... :/