When the difference is two percentage points in a national poll, and the margin of error is 2%, that means that you have a statistical tie.

Voters are closely divided between Barack Obama and John McCain in Gallup Poll Daily tracking conducted June 12-14, with 44% of national registered voters favoring Obama for president and 42% backing McCain.

What does this really mean?

1) This race will be close through the end of the campaign, barring some serious misstep by one of the candidates.
2) For all the claims that Barack Obama is the "candidate of destiny", the numbers don't bear that out.
3) Given the jump in the number of respondents who are committed to neither candidate that has occurred since Hillary Clinton dropped out of the race, there exists a serious possibility that McCain could win the popular vote by appealing to disaffected Democrats, provided he can do so without losing the GOP base.

And let's not forget -- these national numbers don't mean much. It all comes down to the vote in the Electoral College, so it is really a case of contesting 51 separate elections at once.