I believe filesystem alone aren't enough. There must be a means to browse it. For pictures that's simple, but let's consider a Facebook wall (with replies). A

I believe filesystem alone aren't enough. There must be a means to browse it. For pictures that's simple, but let's consider a Facebook wall (with replies). A bunch of text files would be hard to browse, a single big mailbox-like file would be hard to edit properly. Considering that there're multiple OSes, tools and workflow preferences, I doubt there is some universal representation, which would satisfy users.