One of the guys I work with is an ex-optometrist. He said that by 6 months your baby's eye colour is what it will stay forever. Minor changes you see after that I would say are the same as in our eyes - you know, depending on the colour clothes we have on.

An interesting side point that he said as well... By 6 months old, baby's eyes are a big as they will ever be!! They don't grow after 6 months.