I've finally made the decision to switch to Canon and wait for its full frame body (Nikon D3 is out, but it is just too pricy!) So I trade my Nikon 17-55 f2.8 for this Canon's 24 - 70 f2.8 L. I think it is just as sharp as my Nikon, and in some extent out performed it! I just need to save up enough for a cheaper 2nd hand 5D now...
Canon EOS Digital Rebel XTi Canon EF 24 - 70 f2.8 L
1/25 sec f2.8 @ 24mm, iso 100
(Sorry, some hand shake...)
Canon EOS Digital Rebel XTi Canon EF 24 - 70 f2.8 L
1/100 sec f3.5 @ 68mm, iso 400
(I like Nikon's outdoor capability better than Canon, but Canon is for sure less saturated! And again, some unstable hands while driving...)