The D700, which is pretty old by DSLR standards, has just received a firmware update. Unfortunately it isn't anything cool like, updating the Auto -ISO or adding video capability, but it fixes an issue that causes underexposed images in certain conditions.
Nikon claims this is a rare occurrence, but it must be more common than they are letting on, because it's very uncommon for Nikon to release a firmware update fort a camera this old. Which also leads me to believe that the D700 is going to remain in Nikon's camera lineup for a while longer since they are working on fixing bugs in an older camera.
You can download the firmware package from here: Nikon D700 firmware update.
Once it's downloaded follow these instructions for Mac and these for PC.
Of course if you don't feel that your D700 is affected by this problem the firmware update isn't really necessary. I haven't noticed any issues with my camera, but I'll update it anyway and I'll let you know if there's any potential bugs.