A definitive answer can be found here:
http://www.fieldandstream.com/fieldstream/hunting/
article/0,13199,459...
In a nutshell, deer do see color, but no where near as well as humans, due to the mix of rods & cones in their retina. Deer have many more rods, and can see very well in low light conditions, but sacrifice color sensitivity some. At that, their sensitivity is shifted up towards the UV end of the spectrum, with limited sensitivity to yellow. Apparently red, green and orange appear as shades of gray.
That jives with some of the conventional wisdom I've heard as well about never wearing blue when hunting. Besides the whole turkey head thing, deer are more sensitive to blue colors and would probably notice something blue perched in a tree full of red, orange & yellow