We do have a similar equivalent to XEP-0357: http://matrix.org/docs/spec/push_gateway/unstable.html. We can and will make Matrix do smarter than polling though, especially for the case that GCM isn't available. For instance you could use the websocket transport that's available today.
Glad you like Olm :) I think OWS are trying to find a way for their impl to be appstore compatible too, so hopefully the user wins twice over!