From CBS, stuff conservatives already knew already knew:

Was I right that conservatives and liberals are more politically intolerant today than they were in the past? It turns out I was wrong — in part....

People with moderately partisan views were a bit less likely in 2004 to give their foes a 20-or-below than in 1998. But one group — the far left — bucked the trend, getting angrier and more radical over this period. In 1998, 48 percent of people saying they were "extremely liberal" gave conservatives a score of 20 or under. By 2004, this had risen to 65 percent of this group.

And about one in three of these people gave conservatives the lowest possible score: zero. (Note that in 2002, even Saddam Hussein received an average score of eight.) In contrast, the percentage of “extreme conservatives” giving an under 20 score to liberals inched up only slightly over this period, from 45 to 48 percent.

That's shocking, if you think about it: a full third of people who called themselves "extremely liberal" hate people who don't vote their way more than they hate a man who has killed two million, and tortured countless others.