Ok I made it home to check things out... here's what I have found out after messing around:
In the PS3 audio settings menu, remember I've got the latest fat boy, under the Audio Output Settings, there is automatic and manual, but manual says "Select an output format supported by the tv or av amplifer in use. The system will automatically adjust the output to match the selected format." Well, under these formats there is only Dolby Digital 5.1, DTS 5.1, AAC, and then the rest are Linear PCM 2.1, 5.1, 7.1, all in different frequencies. Everything is selected.
So, when I am playing the Dark Knight, encoded in Dolby TrueHD, right now the receiver shows PCM. In the blu-ray menu, you can see PCM is selected, but you can switch to bitstream. If I switch, DD Digital is displayed on the receiver. The difference: bitstream seems louder and fuller than PCM. And, in either format, I can't change the surround settings on my receiver. Why can I not get Dolby TrueHD?