I wrote an earlier post about the operational costs of a divisive primary.
In 2003, outside groups registered 140k new Democrats in Philadelphia for the Mayor's race as a way of upping the vote turnout in a swing state for the 2004 election. Republicans meanwhile were registering in the exurbs and outlying counties. In 2007, no registration happened in the Philadelphia mayoral race because outside groups were involved in the Presidential primary. In Ohio, millions of dollars was spent on TV from the DNC, the media fund, the Kerry campaign, etc, all against Bush. At this point, there's almost nothing being spent against McCain, though he is much less defined than Bush and there's more potential to paint a picture of who he is.
At this point in 2004, there were field operations that had been active for months in swing states. With the exception of labor, that is just not the case today. In other words, a good amount of the blocking and tackling useful in defining and beating a Republican Presidential candidate is just not happening. There's limited local press outreach to dog him, almost no paid media, and very little organizing. This will continue until the primary is over. I would have hoped that one or both of the Presidential candidates would try to steer some focus towards McCain, but that's not happening.
I've since heard from multiple sources that Obama is doing a lot of voter registration, thousands a day. And Obama's campaign can scale its volunteer operation to all 50 states with its easily deployable web tools, though the human infrastructure is not so simple to scale.
Anyway, it's an interesting shift away from the large sustained well-funded outside organization into a campaign which is based on the energy and enthusiasm of thousands. One slight point of pique is that paid Obama organizers apparently cannot post on blogs for risk of being fired, so we have less information than we might otherwise have about what they are doing. And the campaigns are mostly keeping their organizing strategies and numbers to themselves.