One thing the media has so far overlooked

Obama Choosing Biden as his VP choice means that the democratic party, for only the second time since 1948, will be running a ticket without a southerner.
I think Obama is going more for rust belt and industrial democrats this time around than their more conservative, southern counterparts. Being from Illinois and focusing a lot more on working class issues this time around, I think he's trying to make a more serious play for states like Ohio and Indiana than say North Carolina or Georgia. Holding on to states like Michigan and Pensylvania, in which he's still holding marginal leads, while maybe writing off the southern states his campaign had earlier said it would work hard for, does say a lot about the campaign's brush with reality these recent weeks as they've seen Obama's numbers come down all across the board.
Swing voters in Ohio and Michigan will probably be easier to persuade to vote for him than say, conservative southern democrats that wrote him off a long time ago and may not pay attention to his ads or his wealth of field offices in their states.
It is a bold move however, especially-- as I wrote about last week -- given the Democratic Pary's obsession with the south.