There are several treatments that have been developed in the last 15 years, the foremost of which is collagenase. This is an enzyme that breaks down scar tissue. It is injected into the hardened portions of the penis and the area is ‘manipulated’. It is painful, very expensive and not very many doctors are even aware of the option. It does improve most cases where the penis is bent, but has not proven effective for wasping (narrowing).
There are some early results using stem cells that look promising. Florida Urologist Publishes Exciting Results of Stem Cell Treatment for Peyronie's Disease
http://www.peyroniesforum.net/ for anyone interested.