With IPNS, which allows the creation of links whose destination can be mutated by whoever has the private key, you can implement quite a lot of interactivity. You won't ever be able to implement facebook over this platform, but you can replicate all of its functionality by using a tumblog-like architecture. Facebook's design is inherently centralized, and therefore doesn't really fit into the world of IPFS.

The idea is that every user owns their own content, not some central organization. Every user maintains a log of all of their actions, like an RSS feed. Every time they make a status update, that's an item. When they comment on someone else's status update, that's an item. Even when they just like something, it's an item. Each update of the action log would also have send ping to all friends, over some kind of distributed IM like tox. They already need an IM connection like that for messenger.

Given that information alone, anyone can reconstruct the activity of all their friends into a news feed, and post new content. You'd need a lot of client-side leverage, and the ability to upload to the IPFS network from the client, but all the dynamic information is there.

And there you have a fully distributed facebook clone. More resilient and privacy-sensitive and monopoly-averse than even tools like diaspora and statusnet.