Geraghty has a pretty good round-up here. Not surprisingly, the phrase "blood libel" raised no alarms until just today, when Sarah Palin used it. Funny, that.
I hope they are all able to unwind their panties the next time Andrew Sullivan and others use the phrase.
As Michael C. Moynihan points out over at Reason, the term "eliminationist," which has gained a great deal of currency among finger-pointers of late, is one first coined to describe the Nazis.
Given that, perhaps Palin's phrasing was especially appropriate...