The launch date for the 7300 GT's is actually today (Mon.15). I have not been able to find much info on any of the 7300GT's accept for this intruiging little article:
http://www.hkepc.com/hwdb/gf7300gt-1.htm The site is mostly in Chinese but all of the key features and tech specs are in English.
Performance wise the 7300GT is on par with the 6600Since this card is based on the G73 of the 7600 it may be possible to unlock the disabled quad to get the full 12 pipes of the 7600. The stock clocks are 350/667 and can be clocked as high as 450/800, in the case of the Gigabyte GV-NX73T256P-RH version. With a 3rd party cooling solution the OC'ing potential could be much better. As all info to date shows that the 7300 GT will not use TC as the GS did, it has a 128bit mem bus, and uses GDDR3 instead of DDR2 like the GS. For less than $100USD this card should rule the low-end budget market for a while,... if you can find a dealer that sells them yet.