While I've heard the PS3 will be upgraded to 2.0 spec, the addition of DTS MA internal decoding I had not heard of nor do I expect 5.1 or 7.1 analog outputs (which would be rquired for MS decoding) It WILL send LPCM via HDMI, and might do bitstream, but I highly doubt it will do analog audio, I just don't see Sony having put that kind of DAC's into that thing!
A Sony insider has confirmed that DTS-HD MA decoding will be firmware updated for the PS3 along with 2.0, but this will be timed to come after Panny's BD50 2.0 player has had a chance to hit the market and gather some sales.
What's "MS decoding"? Will HDMI not work for you for a particular reason? HDMI can handle 7.1 LPCM.
So far the word (sadly, the PS3's one real fault) is that it won't be able to bitstream advanced audio for external decoding. However the DTS-HD MA update will solve getting lossless out of DTS for most of us.
The PS3 only does stereo analog out. Get the new Panny BD50 if you need 7.1 analog output along with internal decoding (and bitstreaming capability) when it's released.