Not in the Historical Sense
"Palin Explains 'Blood Libel' Comment," by Larry Margasak. January 17, 2011.

Palin may very well know the term, and she meant to use it to refer to those who "falsely accused of having blood on their hands." Palin claims that her using the term wasn't original of her and says that many Democrats have used it. Knowing that she'll receive a lot of hate from the crowd, she refuses to let that get her down and continue to speak her mind.