How about the incident in the senior care center last week? The graffiti sprayed on a GOP headquarters in SC? The two guys in the Northwest who were burning McCain signs...
The list goes on and on.
Take a look at people in your own party Core. Some of the most hateful, vile stuff comes from there. Progressives are all about shutting up those they disagree with. It is a common pattern. Conservatives at least honor the principle of Free Speech and let opposing views be heard.
For example, take a trip to DailyKOS or DU and try and voice an opposing view. See how fast your post is deleted and you are banned.
In contrast, post on FR or other conservative boards with an opposing view and you are engaged in dialogue and debate. The difference is night and day.