Remember how close the election was in 2000 and has we got such a close look at how voting works? Well the same thing is happening for the primary process this year. Because Obama/Clinton is so close, the media pays very close attention to the details of the process that normally get missed. For example, the Iowa precinct caucuses happened on Saturday. Obama picked up a number of delegates, mainly from Edward's people switching over. Now normally this sort of thing doesn't matter, but this race is so close that those seven extra delegates are a big deal.
For further enlightenment on the process, go read Mark Schmitt's take. Basically uncertainty is the key to keep the Clinton run alive. The more we know, the more its clear the Obama is winning. Clinton has to keep things uncertain or else she loses.