A few sources close to Nvidia have confirmed that overclocked 8800 GTS 512MB cards are still selling well and that there are not any plans to cancel these cards at this time.
Last week one of our colleagues reported that Nvidia banned overclocking on these cards and made us investigate. Well, as of today these cards are still selling and you can still overclock them.
We would be very surprised if Nvidia ever bans the overclocking as it has many vendors that cannot survive without the overclocked cards.
However, there might be some action against the 720 or 730MHz cards as certain two Taiwanese fellows are maybe pushing a bit too much.