SilverWook said:

Since many early Blu Ray titles have nice uncompressed PCM tracks, all these dueling audio codecs seem unnecessary. But they had to find a way to make my less than five year old receiver obsolete didn't they? ;)

I can hear the difference between Dolby Digital and DTS on DVD, but hearing any subtle differences on Blu hasn't happened for me yet.

With regards to multi-channel PCM, I think one of the reasons it has been dropped as an option by most studios is that firstly it took up too much disc space (Stereo 24bit WAV is about 2Mbps, so 6 channel is about 6Mbps). Also, in legacy AV receivers, you don't get a proper 5.1 track, just a Pro-Logic track, so studios still had to include something like a Dolby or DTS track on there anyway.