slrgear.com recently posted a 5-sample review of the Nikon 50 1.4G on a D700. I'd been waiting for it since a while ago when they promised to do it after a similar review of the Canon 50 1.4 on a 5D. I don't think there's any question about which wins out wide open.
Nikon: http://www.slrgear.com/articles/variation_nikon50f14/nikon50f14.htm
Canon: http://www.slrgear.com/articles/variation_canon50f14/canon50f14.htm