Right, but my setup reports DPLII (or any other "virtual surround mode" of my choosing) whenever multi-channel is unavailable. It's definitely receiving a proper 7.1 audio stream from the PS3.
Neither of those report multi-channel. They both come up as stereo (which can be used with various DPL, DTS, and other virtual audio options). The receiver treats these very differently than multi-channel. The front display only shows two speakers as active when using DLPII, for instance, despite distributing the audio between all of channels. Downpour definitely shows up differently.
I should also note that I have the receiver handle audio decoding for Blu-ray discs which report DTS MSTR HD or the Dolby equivalent. For games which use multi-channel it reports multi-channel while the 360 specifically displays "Dolby Digital" which I push over to DDEX for the extra channels.
I'm actually kind of an AV enthusiast on top of a gaming fan so I know my setup very well.