AnandTech: Understanding 8-channel LPCM over HDMI: Why it Matters and Who Supports it
Well AnandTech showed up with a nice little why proper HDMI audio support matters article. The article has some good graphics to show how the flow of protected data works. One nitpick is that they seem to use "protected audio path" synonymously with support for bitstreaming the advanced audio codecs, which isn’t accurate. They also spend all their time talking about audio from Blu-ray discs and forget to mention 7.1 HDMI support also benefits HTPC gamers because then gamers have a digital connection that just works, no lossy recompression (ala Dolbly Digital Live or DTS Connect), or analog connections needed.
Also for those wondering what happened to those HDMI enabled sound cards, which do support PAP, and bitstreaming, AnandTech has a little nugget of information there too: