Via Mark Ambinder, Obama transition aides say he will address critics who think he needs to scale down his amibitions: 

The fundamental question of our time ... is not whether government is too big or two small, it will be whether it works.  

The address will not have policy specifics, nor should it. It will instead make broad statements about Obama's vision for the country. And it sounds like that vision is entirely consistent with what we've heard from Obama for the last few months: He's thinking big.

--Jonathan Cohn