I noticed this as well but would be interested to see some specific examples of it. Numbers?
Some of this may be due to a more concentrated GOTV effort in particular Democrat-friendly areas, rather than ads. One way to test this would be to compare the 2004 and 2008 out-of-swing-state portions of multi-state media markets with other media markets in that non-swing state.
Take the Philly media market, for example. It was probably one of the most expensive and extensive media buys during the campaign. Obama appears to be up big versus 2004 in the PA portions of that market - including the Allentown portion of that market. Yet, at a quick first glance, in New Jersey (which is divided into the Philadelphia and NYC markets), I don't see any major difference in the swing between the South Jersey counties in the Philadelphia media market and the North Jersey counties in the NYC media market. I'd have to crunch the numbers to be sure, though.
Some of the media buys were probably on PA local cable.