But jas, it is only useful in shoring up an idea that is completely false because it is a comfortable illusion. What is useful about that?
I have heard plenty of news reports about people needing to be careful to protect their stuff when they store it in a place they don't control. There is a lawsuit against the FBI for data that got trashed when they shut down Megaupload
http://techcrunch.com/2012/01/26/pirate-parties-organizing-lawsuit-again...
But it's doubtful any of that will restore the lost information, it doesn't change the fact that people need to beware and not have any illusions about trusting data to free services, and it has nothing to do with the core issues in this case, which have to do with how far a third party can go in limiting other people's expression and essentially changing the public record.
And far from calling it property, I'd suggest that discourse in social networking sites are part of the de facto public record, despite the fact that they are on sites which are privately owned.