I still don't see why this whole "she didn't have a motive" argument is coming into play. Look at the mothers over the years who have killed their kids for either no reason or some crazy reason. Susan Smith for example, her motive was, to dispose of her children so that she might have a relationship with a wealthy local man who had no interest in a "ready-made" family.
Yeah, Casey Anthony is REAL innocent. While her daughter was missing, she didn't feel the need to report it to anyone. In fact, she decided that she would just go out to the clubs and party a little bit. Yeah, that has innocent written all over it.