The weighted ball program has been the topic of some arguements within the baseball community.  Some coaches think that using weighted baseballs will cause injury to pitchers.  Other coaches believe that the weighted baseball throwing program can add strength and velocity.  The only thing I have to say about this is that I have used the weighted baseballs before for a few months.  I never threw them.  I only used them going through dry drills, trying to work on arm speed and arm strength.  I thought they were helpful and they did not hurt me in anyway.  If anything they made me feel better.  As for throwing these baseballs, I do not know.  I have never used them in a program like that.  So, alot of pitchers want to know if you can get hurt by training with weighted baseballs.  Well, the answer is yes, if you do them improperly.  That goes the same for anything though.  You can hurt yourself throwing a regular baseball or weight lifting if you do it wrong.  Weight lifting and throwing (if done properly) are injury prevention methods.  Therefore, I think that if weighted baseballs are used correctly, with good mechanics, and moderately, then they are a good way to improve velocity and arm strength.  They could even prevent you from injury.