I just saw something on the discovery channel just about 30 minutes ago on chick processing plants. They put these hours old babies on a conveyer belt shell and all. The babies fell through the cracks and then down another belt and dropped off into the shipping boxes. I almost cried. Poor babies!
BUT they did show how they sex them. Look at their wing feathers. If they are all the same length it is a roo. If they are staggared long short, long short it is a hen. I thought it was so cool!
Oh I just did a google search on it. It seems that this method used to determine the sex of newly hatched chicks is only possible if a female from a slow-feathering breed is crossed with a male from a fast-feathering breed. So I suppose it wouldn't work on all chicks. Oh well...