I'd say from October onwards we will start hear much more again....
Hopefully they'll share a few more interesting tidbits before then though, or they risk being outmarketed by the alternate OS's (let alone the major ones).
Canonical especially is very astute at it, Mark Shuttleworth styles himself after Steve Jobs, he knows what his doing in that area.
Already Ubuntu and Tizen has more mind-share, they can't afford to let that lead become too big...