VR Zone claims the GeForce 8600 GTS, 8600 GT and 8500 GT will all three be launched on April 17th. They state graphics cards makers have already received revision A2 GPUs from NVIDIA for mass production:
We can expect cards to reach distributors and retailers in 2 weeks time ready for mass availability in the market. The performance of the G84 and G86 cards are pretty ideal so far and card makers are satisfied. Using a Core 2 Extreme QX6700 processor, the 3DMark06 scores for 8600 GTS reaches 7K, 8600 GT is 5.9K while 8500 GT is 2.9K.