Obama got 38 percent of the vote in Iowa. Not only is Iowa only one small state, but 38 percent of the vote is way less than half. Nevertheless, based on that plurality he was about to march to the nomination. As a result, while Obama continued to hold his own in terms of his baseline level of support, all the uncommitted people -- supporters of minor candidates, undecideds, some soft Edwards people -- voted for Clinton to keep the race going. In Iowa, a similar dynamic probably helped Obama. People knew that a Clinton win might end the competition, so Obama can, so to speak, the benefit of the doubt. Unlike most political bloggers, most voters haven't been following this thing since the first quarter of 2007. A lot of them want to see how the competition plays out.
Actually, I think most of the prominent liberal bloggers are also interested in seeing how the Obama/Hillary contest plays out. Bloggers like Kos (for Obama) and Matt Stoller (Edwards) have stated preferences, but they've largely refrained from openly campaigning for "their" candidates in their blogs. Contrast that to right-wing blogger Hugh Hewitt who has been openly shilling for Mitt Romney or any number of conservative blogs that have been campaigning against Huckabee.