The most recent Harris poll, showing Bush ahead of Kerry by 10%, looks less-and-less like an outlier. 51%-41% is within the MOE of this poll.
The general trend of all the recent polls is also important. President Bush seems to have received a 5-7 percent bump after the Reagan funeral. Even today's Gallup poll (Bush +1) shows this.
The question is whether he can build on this momentum.