Gallup shows McCain leading by 2 points:

Gallup Poll Daily tracking from Aug. 23-25, the first three-day period falling entirely after Obama's Saturday morning vice presidential announcement, shows 46% of national registered voters backing John McCain and 44% supporting Obama, not appreciably different from the previous week's standing for both candidates. This is the first time since Obama clinched the nomination in early June, though, that McCain has held any kind of advantage over Obama in Gallup Poll Daily tracking.