gst-plugins-bad-0.10.1 ebuild compiles on amd64 with the ~x86 keyword. It also seems to not break my system and in fact lets me listen to aac/m4a files in amarok 1.4beta2 along with gst-plugins-faad plugin. Is there a good reason why it doesn't have a ~amd64 keyword so other amd64 people can test it?
The reason is gstreamer didn't ask us to test it and keyword first. Keyword added.