OK, the actual Coen Brothers will not be at the AFI in Silver Spring, as far as I know, but the theater is putting on a retrospective of many (all?) of their best movies. 'Course I'll probably never go to any of the showings since I never go to movie theaters. I think the last movie I saw in a theater was ... um ... maybe Lady in the Water? If that's right, that was in 2006.
Anyway, here's the info about the Coen Bros. retrospective.