Obama's call for a "new kind of politics" based around this kind of mutual understanding and an end to an active demonization of political opponents discomforts a lot of people on the Left who see echoes of Lieberman-esque capitulation and collusion in the cloak of bipartisanship. And Obama hasn't done enough to calm these worries by staking out his territory on the Left on the policy side.
I went to an Obama fundraiser yesterday at the 2400-or-so capacity Electric Factory (normally a concert venue) yesterday. His rhetoric is interesting, as he seems to be able to seamlessly shift between Liebermanesque what's-most-important-is-that-we-all-get-along rhetoric and radical "let's take to the streets and burn shit down" rhetoric (I'm exaggerating on both sides, of course). The inclusive rhetoric doesn't just worry people like me because of policy concerns, it's that one worries he's confusing idealism with reality.
The crowd was diverse across age and race, and Obama certainly has his fans.