Paul,
I was suprised to see the D700 listing for around $3500, definitely a lot of camera for the money, especially when you consider the pro-level specs.
My only beef is the way Nikon handle RAW files in long exposure images. Have a look at Christian Buil's website
www.astrosurf.com/buil for more information (look for the 10D/D70 comparision). Still it doesn't stop people getting great astro results from these cameras.
Terry