In continuing with a "Deal of the Week" through December, Microsoft is putting the Foo Fighters album The Colour and the Shape for Rock Band on sale for 1200 MS Points (down from 1600).
This 25% discount is available to Xbox LIVE Gold members for the week. Here's a link to the product page on Microsoft's web-based Marketplace, but you need to be signed in with your Xbox LIVE Gold account to see the discount.
The individual songs from the album have not been discounted.
Planning on picking this up? I might, but I'm going to have to take a look at the note charts again.