I listened to the interview and feel that she made a few good points.
First of all, a few days before, Baby P was examined by a doctor. If there was abuse, it wasn't obvious. (and also believe Baby P saw his father a few days before also?)
Sharon Shoesmith points to the fact that the police and the CPS agreed there wasn't enough evidence to prosecute the mother.
However, what Sharon Shoesmith fails to mention is that social services operate on a different standard of evidence...
Listening to the whole story, I don't know what social services could have/should have done.