It seems like this might have gotten posted twice, so I'll just cut and paste what I wrote on the other one here, too. Not sure about a lot of the answers you're getting, cause this is normal. If any of you guys got chickens who actually grow feathers on their breast bone please let me know, cause I have over 60 chickens and none of mine actually grow them on their breast bone.
Very normal. 3 week old chickens tend to look a little ragged while they're getting all there feathers in. I've found that Orps and Australorps look the most crazy. Also, here's a quote from Gail Damerow's book "Hatching and Brooding Your Own Chicks":
"Unlike a mammal's fur, feathers do not grow over the entire body surface of a chicken or other type of poultry. Instead, the feathers grow in small, symmetrical tracts and fan out to cover the body. The feather tracts are separated by featherless areas in which some down may grow, even in mature poultry."
There's more, but that pretty much gets the point across. Also she has a diagram on the page showing where the feather and featherless tracts are. One of the featherless tracts on a chicken is the breast bone. They'll start filling in a lot more as they age and their feathers fan out, but for right now they might look a bit funny.