Here's the view from a new Democracy Corps memo (pdf) analyzing the latest round of polls:

An objective analysis of averages derived from all of the polling conducted and released since Labor Day, as well as trends on a number of key measures, indicate there is undeniable truth to the notion of Republican gains...

However, the memo continues:

there is no consistent data indicating that the shifts toward Republicans have come among Independents or swing voters. Bush and the Republicans in Congress reached their low points this spring and summer because of deterioration within their Republican base. As the campaign gathers steam, we would fully expect these voters to return to the Republican fold or to alternately simply drop out of the electorate (and thus not be measured in likely voter surveys). Either way, until Bush and the Republicans make significant inroads among Independent voters, they will not be able to make up the significant deficits they still face before Election Day.

I agree with the first part of the final paragraph but not necessarily the last part. One of the key insights of the Bush '04 team was that the election would be won by focusing on expanding the base, not spending vast amounts of time and resources trying to win over a small slice of independents and undecideds.

It's true that Bush and the GOP's standing among Independents has deteriorated over the last two years which makes the current political climate very difficult, but the flip side is that turnout will be much lower this year than in '04, putting even more of a premium on getting Republican base voters to the polls on November 7.