Obama hit a 46% approval rating in the Gallup Poll today, with 45% of respondents disapproving of his performance.
He's been bouncing around this range since early December, so this isn't a precipitous fall, or one that necessarily reflects actual movement.
But it sure is hard to make the case that all this health care talk is, at this point, anything but a political liability. Although Joel Benenson is arguing just that today. (Source)