I don't think dogs are color blind persay, at least they don't see in just black and white. They don't have as many color receptors in their eyes as humans do..so it is thought that they can see color..but not the same way we do. They can also see better in low light conditions than we can...
I have also heard dogs can't see the television, but I know this isn't true because Lucas tried to attack a dog on television..he knew exactly where it was
Anyway, here is an article that explains dog vision in detail...
http://www.nahra.org/nahra/vision.htm
Toward the very bottom it discusses color vision in dogs.
Lucas loves his Kong which is red. After he started really playing with it..I have noticed he gets my sons red toys too....for example...a small Elmo and Po the red teletubbie. I have saved both Elmo and Po from Lucas often since he started playing with his Kong. So I think he can see red in some form...maybe not the way I see it...but he definately can tell all these red objects are the same color