Realplayer-10.0.3 works fine, is marked testing for more than one month and there are no open, amd64 specific, bug reports. Please add stable keyword for this version or better for media-video/realplayer-10.0.4 (security bug #89862).
10.0.0.3 will not marked stable now as it will disappear soon (because of the security flaws), 10.0.4 however has to be tested 30 days before it will be marked stable. (just following our policy)
Realplayer-10.0.4 is now quite a long time in portage without any open bugs. I think it would be a good idea to mark this version stable in order to have at least one stable version in portage.
Realplayer-10.0.5 now marked stable, thanks