It looks like Lawrence Summers has decided to do the sensible and honorable thing and withdraw himself from consideration to be the next chair of the Federal Reserve. Knowing how clearly he was the President's private first choice and how long Summers has coveted the job, this must have been a very tough call for him.
But it's also the right call. It had become clear that there was enough hard-core opposition to Summers from Democratic Party senators that getting him confirmed would be a tough political lift. The country's monetary policy doesn't really need that kind of chaos, and the Obama administration could ill-afford to be spending political capital on that kind of thing. In this case, the best way for Summers to serve the country and the causes he believes in was to step aside.
The interesting question now is: If not Summers, then who?
Janet Yellen has always been the obvious choice and in my opinion she's still the obvious choice. But given Obama's apparent preference for someone he's worked closely with, I don't think you can rule out Timothy Geithner. This strikes me as a mistaken preference—not particularly as a knock on Geithner but as a knock on Obama's understanding of what the job entails. Geithner does not seem like someone who's especially interested in monetary policy, and at the end of the day though the Fed chairmanship is about a lot of things it's mostly about monetary policy and the job should be held by someone with good ideas about monetary policy.