According to Charlie Cook, here are the latest poll numbers:
Numbers: Bush Approval/Disapproval: Bush Kerry Nader Bush Lead: Bush Kerry Bush Lead (in percentage points)
Aug 3-4 Fox News/Opinion Dyn 43/48: 42 46 2 -4: 43 46 -3
Aug 9-11 CNN/USA Today/Gal 51/46: 46 45 5 1: 48 47 1
Aug 15-18 CBS News 46/45: 45 46 1 -1: 44 47 -3