(via reddit) It's actually been there for quite some time. I know, because my girlfriend's mother lives in Tucson. It's probably via the radio station, not Limbaugh. Though, I'm sure he—or his "people"—had to approve it before it was erected. Yippee ki yay, motherfuckin' liberals.
update: Gawker reports that KNST took the board down Monday. Too late.
Previously in Tucson: Dickman's Meat.