I heard about this today on my Fresh Air podcast.

It's the story of Chess Records in Chicago in the 50s and deals with Muddy Waters, Etta James, Chuck Berry, etc, etc. Looks like it may be pretty decent.

Here's a link to the website and the trailer page.

Cadillac Records (http://www.sonypictures.com/movies/cadillacrecords/)

Click on a picture there to reveal the internal links

Everything I've been reading about this movie sounds like it's a must-see.

This review is very, very interesting:

http://www.buffalonews.com/entertainment/story/515106.html