^^ what lil kim said
in practical application, the only issue is that the stuff is sent as lpcm, and if it is 5.1, but you have a 7.1 setup, the ps3 sends 7 channels, but the last two (rears) are muted. if you play mp3s, it is two channel, but if you have a 7.1 setup, your receiver reads it is getting 7.1 channels, but all but the front l and front r are muted. the issue is that this means alot of receivers cant post process the lpcm audio, 'cos most just pass the lpcm through. but everything works, it just gets streamed via hdmi as described above... there are other options and workarounds, but they involve tweaking the settings in the ps3, and that can be a burden when using the unit for various apps everyday; my guess is that a future firmware will resolve some of this, like only streaming 2 channels of lpcm when playing stereo tracks (which would then allow users to play with their receiver's post processing settings)...