Whether or not they will beat AMD to that mark isn't clear. AMD's RV870 chip, which will be a 40nm part, is also scheduled to come out around the same time – roughly Q2 of 2009. Cards from both companies will see the obvious reduction in power consumption, so the real question is which company will produce the faster card. At the moment, it seems like AMD will – because Nvidia is apparently going to be using their existing G92 architecture to manufacture 40nm parts.
Given that the existing Radeon parts are doing well to beat the G92, things are not looking up for Nvidia.