Wow. Sarah Palin really has no soul. Does she know what "blood libel" has historically meant? It's accusations made up against Jews specifically- the most famous one is that we drink the blood of Christian children for the Passover Matzah- in order to justify killing Jews. No one is trying to kill Palin. They're just criticizing her.
Clearly Sarah Palin is not to blame for the events in Tucson, although I'm not sure I've heard anyone suggest that she is. But the target map she put out- which included someone who ended up getting shot- was a horribly short-sighted and vile thing to do, and there's no responsible reaction for her to have now except to apologize. But she can't, because it's contrary to Sarah Palin's brand. She can never, ever apologize for anything.