Patterson et al have published a study in Nature (press release) indicating that the common ancestry of humans and chimpanzees is more complex than suggested by recent and historic data interpretation. The new study, which utilized a large number of high fidelity DNA sequence comparisons, presents data that suggests that the common ancestor population split once, came back together to form a hybrid population, and then diverged once again to form the modern human and the modern chimpanzee. DNA sequence similarities (particularly on the X chromosome) indicate that the first population break resulted in the modern chimp line, and that the hybrid population evolved into the modern human.
..."Don'tcha realize sweet baby? Woman I don't know... which way to go. Woman I can't quit you babe." (from "I Can't Quit You Baby", a blues song performed by a number of great artists)