The McCain and Obama campaigns are obviously out testing strategies for their general election matchup. Obama is speaking much more aggressively, calling McCain for example a "creature" of Washington and lambasting his stance on the Iraq War. McCain is getting tag team help from no less than the President of the USA himself, GW Bush, who is calling Obama's approach to foreign affairs the "appeasement" that Bush says has historically failed in dealing with other countries.
As usual this election will probably be won or lost with the indecided voters who have yet to make a firm decision. A key indication of the outcome will be how the Hillary Clinton voters react to her likely demise. If, for example, West Virginia and other conservative southern states go towards McCain the Obama campaign will be pressured to "conservatize" Obama in ways that won't make his key support base happy.