Personally I think its nice to see this kind of creation tool decoupled from a social network. I am hoping it can take Vine like videos, which I can keep and redistribute in a method of my own choosing.
I imagine this will come with a Messages App though the UX around those integrations is terrible the standalone app will be enough.
Messages can only be used by Apple customers, but this is not indicative of a social network and would detract from the value of a legitimate social network.
It's exactly what we criticized Microsoft for in "embrace and extend" back in the 90s.