OMAP4 has been announced in February 2009, with silicon available from February 2010 and volume production in late 2010.

EDIT: Though it might be counterintuitive, dual core processors might actually mean better power saving in certain scenarios (having two well utilized cores at 500MHz can be less drain than a single core at 1GHz (as power consumption increase is not linear).

EDIT2: OMAP4 brings also many more interesting things, not just dual cores and general efficiency - take for example the video/image segment, stuff like multi-display output, support for image stabilization, 1080p level of video muscle, picoprojectors and even 3D content should that become an important thing.