Information or MisInformation

Polls show Obama-McCain race tight as campaign begins - CNN.com via kwout

As a reader, should I believe stuff like the above or not? Let me point out that most students are out of school now and yet many of them may be registered where they attend. So I'm guessing students are under sampled in this poll and there is sampling bias. Do the reported results correct for the bias or not? I have no clue. I can't get that from the story. If, ultimately, Obama gets a big kick in the polls when students go back to school in the fall, the polls will report that as momentum when all it may be is mis-measurement during the summer.