Nikon has introduced a memory buffer upgrade for the D3 in Japan. At current exchange rates, the cost of this buffer bump is a bit under US$500. (As I write this, apparently NikonUSA is about to announce the same thing, and other subsidiaires are piping in, as well, so it should be system wide soon.) Since the original buffer isn't really all that restrictive to JPEG users, the upgrade would probably be of most interest to NEF users, where the boost is significant (from a minimum of 16 images with the stock D3 to a new minimum of 37 images; the JPEG limits almost 130--the camera limit--for all settings with the new memory). To get the upgrade, the camera has to go into a service center, and estimated turn around is a minimum of two weeks.
So the question you're probably asking is "what the?" Well, one thing comes to mind: Beijing. But I think that's more just the timing of the announcement. I suspect the real story is a little deeper: what makes me suspect that the lower D3 prices lately are a way of clearing out the old model for...wait for it...the new D3. Maybe it'll be called the D3s, but even if it isn't it makes good sense to put a few minor tweaks into the D3 to restore it back to its rightful place above the D700. High on the list would be sensor cleaning, even more performance (that memory buffer is a good start), and maybe a dedicated Info button to get to those key settings faster (ala the D700 and an upcoming camera I won't name ;~). Sit tight kittens, mommy appears to be bringing you another meal to consume.