Mutt Lauer brought up the story on the Toady Show this morning, where he interviewed the law student Limbaugh was insulting. No mention of any bomb threat. Lauer is one of Limbaugh's golf buddies, he seemed disgusted over the comments.
On edit, there was a poll out recently that listed Rush as "the most hated radio talk show host". I understand that his ratings have been dropping over the years, too. Got to wonder if this was the same sort of act of desperation that we're seeing out of the GOP, which is on a similar trajectory.