I tend to not put too much weight on the daily numbers, paying more attention to the weekly averages. By that measure, Obama has been on a steady downtrend since he took office.
He did a big slip from January to June, stayed static through the summer, and then in the fall resumed his down trend.
The current state is important in what it indicates about the future. Obama likely has a small percentage of strong supporters left among the white middle class. In parties and in the work place, people increasingly can make disparaging remarks about Obama without triggering a tirade from a strong supporter. This will work to further erode his popularity going into the 2010 election season.