Too bad almost none of the commentators understand common facts about sports physiology and pharmacology. For example, the CORTICOsteroids given the tennis players for injuries would tend to make them weaker, not stronger.
Serena took Prednisone, which is a corticosteroids, that's true, but the problem is that she was positive to two Prednisone active metabolites: Prednisolone and Methylprednisolone. Those are steroids (who could think that Serena took steroids?) and in this case she was cleared because she can say "I didn't take those banned substances, I'm positive as a side effect of that other substance, allowed under restrictions". It is Lance Armstrong all over again to me.