Neurosurgery is an early match. I asked my friend who matched at a neurosurg program why there are some spots in the main NRMP match. His explanation to me is that these spots are actually filled. These applicants are apparently required to register for the NRMP, but some don't realize it. Thus, there appears to be open spots at these programs. Sounds kinda wierd to me, but I know its a early match, so I would tend to believe him.