Permissions on /dev/dsp* don't allow a regular user to play audio files (regular users must be able to read and write to /dev/dsp*, or a regular user must belong to group 'audio')
um, not sure what the bug is here...
I would suggest either changing the perms or making a note in the documentation that a regular user must also belong in group audio.
It is already in the Desktop Configuration Guide-- http://www.gentoo.org/doc/desktop.html and scroll down to Code Listing #22