I have an older Sony reiver that has HDMI, but doesn't pass sound through it. It requires an optical audio cable in addition to the HDMI cable. Make sure that you're receiver passes both sound and audio through the HDMI cable if you go with the PS3, because I doubt that it will have optical audio cable connections.
The PS3 does have an optical out. It can send video over HDMI while the audio (lossy core only, but that's a limit of optical) is bitstreamed to the receiver. I had this setup before I got my new receiver. It worked fine. Actually the new 3.0 firmware, can have both the optical and HDMI active at the same time, before you were limited to one or the other.
I vote for PS3. For technical reasons (mostly involving audio mixing, and 100% of the Blu-ray feature-set), I feel it is still the best player out there. better than even the Oppo; unless you plan to watch a lot of DVDs, and desire the best possible upscaling. Even then, there's no reason Sony couldn't improve their upscaling because it is done entirely in software, and has been improved in the past.
