This adaptor is required if you want to use the Apple 30” Cinema Display with the new MacBook models. So, you might have to wait till Christmas to hope getting such adapter in shops, or at least from the Apple Store… Maybe Apple is acting on purpose to push owners of the new MacBook models to purchase the new 24" LED Cinema Display...
If you consider that this is the only display which can work natively with the MacBook models, while all other displays (including previous Apple Cinema display) will require adaptors. We are still waiting for the missing adaptor: Mini DisplayPort -> DisplayPort (or HDMI) which will allow the new MacBook models to be plugged to HDMI peripherals...but none of them is branded by Apple, so why would you expect such adaptor to be developed by Cupertino...