The GeForce 7900 GS has been available for a while now in pre-built PCs but according to HKEPC the card will be launched for the retail market later this month:
Much like the GeForce 7600 GS is a cut-down GeForce 7600 GT, the GeForce 7900 GS appears to be a cut down GeForce 7900 GT. It reportedly runs at 450MHz with 20 pixel shader processors, seven vertex shader processors, and 256MB of memory clocked at 660MHz. In short, the card runs at the same speeds as the GeForce 7900 GT, but it shaves off four pixel shaders and one vertex shader.
Pricing on the GeForce 7900 GS will supposedly reach almost a hundred bucks below the GeForce 7900 GT to the $179-199 range, which could make the GS a very appealing mainstream card.
The GeForce 7600 GT will also get a price cut to $130. More info at The Tech Report.