As someone who spent nine years as a political consulant, using polling data every day and designing dozens of polling instruments (the sets of questions asked of voters), I'm always very wary of the way the mainstream media reports about polls. (See my earlier Weekly Planet take on the subject here.) There are just too many ways for campaigns to manipulate the outcome of their polls to their own advantage.
And I've yet to meet the reporter who really understands how polling really works.
Even the indepedent academic polls are subject to great limitations. For an excellent example of this, read Thomas Croom's dissection of the latest Quinnipiac poll in the governor's race here. Croom is the politico behind PEER Review, the best conservative blog in the state.