I think the intention with OS4 + PS3 was that "what if Sony had used OS4 as their proprietry OS for the PS3"
The thing is on a PS3 + Linux you can do quite a lot, it's a pretty much full blown computer if you add the keyboard and mouse. But OS4 is a lot more efficient in the limited memory and graphic hardware direct access hence the proposal. You can run open office, surf the web, download and watch/listen to movies/music. And obviously play PS3 games (which look better than pretty much all PC games running on 3 figure PCs). So what else do people do with PCs that this setup can't do?
In my opinion, the PS3 OS doesn't have to be Linux or any other recognised OS out today to the general public, it's not like people buying a PS3 will go "oh man that thing won't run XP/OSX/Linux" haha they don't give a crap they want a responsive and reliable environment running efficiently on the available hardware. And hell if it did happen, maybe it would allow people to write games for it a la 80s bedroom coders of the 8bit era? Let's face it Sony needs a good answer to XBOX Live Arcade really aswell.
But it will never happen so it's kind of a non-starter of an argument really no? But well let's face it why would it be a bad thing? Who cares about Linux in the free market of consumers with money to spend, all people want is the best possible solution and of course it's 1 LESS choice for a piece of hardware with a decent OS you can go in the shops and buy ready to use :-(
