I can understand McCain turning down the VP spot, because he currently has a much better job and could get a good position in a Kerry administration. But Edwards? He has even moved to the DC area. He had to give up his Senate seat to run for president and it looked like he might not have won it anyway. The Clintons, from what I remember, suggested that he move to DC and hang tight. I would think that the VP would be most advantageous to him, unless the Clintons have something else for him up their sleeve.
He probably moved to DC because he ain't welcome in North Carolina anymore, and because he's pursuing a lucrative career with some high-profile Beltway clients.