When listening to the podcast he didn't say that color output changed with the update. He just said that developers are now actually properly targeting the machine and not doing quick and dirty 360 ports, and that tons more ram is available. Since people are saying that not much new ram has opened up, maybe he's referring to the state of things now vs when the console launched.
Also, isn't the difference usually because the 360 outputs with a gamma of 2.5-2.6 while the PS3 outputs with a correct gamma of 2.2. So if you design your textures to account for that gamma they will look really washed out if you don't fix them for the PS3? That's what I read anyways. And considering how the 360 crushes black at the same settings that everything else in my HT, including my PS3, look perfect I'm inclined to believe it.
Also, has it been discovered how much ram the OS takes now? Or do we just know that it takes less than 72mb now?