As always, Bush puts politics ahead of policy. This news, leak, whatever, is clearly indicative of that. It's meant to help McCain out--in the same manner as LBJ's bombing halt nearly threw the election to Humphrey in '68. Expect more of this:

The Bush administration is considering the withdrawal of additional combat forces from Iraq beginning in September, according to administration and military officials, raising the prospect of a far more ambitious plan than expected only months ago.

Not only that, McCain is now moving to the center in many ways, including this article from the Times as well:

Senator John McCain in a wide-ranging interview called for a government that is frugal but more active than many conservatives might prefer. He said government should play an important role in areas like addressing climate change, regulating campaign finance and taking care of “those in America who cannot take care of themselves.”

Everyone is moving towards the center now. That includes Obama, especially in regards to his cave in on FISA.