So, it seems that the new Nikon D800 (and the D7000) are experiencing a slight hiccup. Seems that the US and Canadian governments have issued a recall over problems with the battery. Apparently there is a burn hazard with the batteries of these two cameras.
For more info, check out the article on Engadget, but if you have a D800 or D7000, check out Nikon’s website to see which batteries are under recall. Better to be safe than sorry.