On the Millions website (http://www.themillions.com/), you can find all sorts of book-related discussions and reviews. The following link is particularly intriguing. Sharon Steel wrote about publishers and authors who propose playlists that are directly (or indirectly) related to their characters and books.
What do you think? Would you want your e-reader to pop up with music at certain moments of a scene? Do you want to know what music the author was inspired by? Is music too personally subjective to have presented as part of the 'package'? In my case, I hate it when a book cover shows an actual person; it interferes with how I picture things. Along that line, I don't think I'd want a music tie-in necessarily...and I would especially dislike being pushed to understand a character by listening to their music (I would want that to be the writer's job). Wouldn't it open up a whole new industry, catering to book interpretation, which would then be subject to costing the reader money? Optional, maybe. But required? No way.