Not in the current 'design phase' they are in. It just wouldn't fit on something like the ipad. The white ipad with a colorful smart cover does the trick, I think, for people who want some color.
Colors make sense on the small, pocketable, 'fun' products. On the more serious stuff, I don't think they will do it as long as they are doing the glass, aluminum, black and white thing. I am sure their design vision will shift again in the future, as it always has in the past, and perhaps they will incorporate some more color options at that time.