...and Red Cloak is the source of the 96mb claim. Nuff said really
But I agree, it would be nice to find out or at least speculate on how much memory is reserved for the PS3 OS. It's just, well there was one person in that thread who could have known and also gave an answer, but nobody decided to pay any attention. Fishie suggested it to be around double the size of the 360 OS, or ~64MB.