If you check out the draft (http://tools.ietf.org/html/draft-ietf-httpbis-http2-04), it looks like either the client or the server is able to initiate and send data along the HTTP/2.0 streams.

And in Section 2.2:

>HTTP/2.0 provides the ability to multiplex multiple HTTP requests and responses onto a single connection. Multiple requests or responses can be sent concurrently on a connection using streams (Section 5).

This requires supporting client-initiated requests over an established connection.