Remember Nikon's problem with the black point clipping?
http://forum.orpington-astronomy.org.uk/index.php?topic=8917.0
The Nikonhackers group now has a firmware patch to deal with the issue:
http://www.cloudynights.com/topic/461871-nikonhacker-close-to-black-point-hack-on-d7000/
This means the Nikon (plus firmware patches) can now be considered as a serious astro-imaging DSLR.
With Nikon's ISOless read noise, high QE and low thermal noise, Canon now has a bit of catching up to do.
Mark
Excellent news! I must give this a go.
Some more useful info in this blog:
http://landingfield.wordpress.com/