I regularly check the SVN builds of Amarok my favorite music program (if you are using linux, go check it out). Since I also use Gentoo, I just needed to have a good ebuild for it. I found a very good file on the Amarok forums, but had some small problems with it (it did too much), so I made a small update.
If you are interested, here it is.
03/06 small update: on the Amarok forums someone pointed out that the same result could be achieved in a more elegant way. The download now points to the more elegant file.
06/08 update: Andrew pointed out that you need to update the ebuild with a couple of things. Please read the comments for the information. Personally I didn’t have any luck lately since the process now seems to need unsermake and QT4. I am working on that.