Recently I had a chance to build a Spotify App. I had a great time and learned a lot. I just wish they had some code for their patterns they ask for and I am sure you feel the same way. For an example in the UI guidelines they talk about using a "standardized track listings", but don't really tell you how to do it. So I decided to create my own pattern library for Spotify Apps. I may be off on color, sizes, etc, but I am only going off of what they currently have. Remember this is only a starting point.
I am currently hosting the site at spotify.kennedysgarage.com