Wanda Sykes' vicious, venomous comedy (which gave Barack Obama such hearty chuckles at last weekend's Washington Correspondent's Dinner) certainly wasn't the first time we've seen insane rage displayed by the Left towards those with whom they disagree.
In this Front Page Magazine piece, Ben Johnson gives a review of some of the more notable examples plus a link to a Michelle Malkin article which gives even more.
Warning. You might want to take a Pepto tablet before reading what liberals consider suitable political discourse nowadays.