When your right wing/tea party acquaintances blame Obama for the S&P downgrade, Obama’s only blame is negotiating with them. But don’t quote me - quote S&P:

Compared with previous projections, our revised base case scenario now 
assumes that the 2001 and 2003 tax cuts, due to expire by the end of 2012, 
remain in place. We have changed our assumption on this because the majority 
of Republicans in Congress continue to resist any measure that would raise 
revenues, a position we believe Congress reinforced by passing the act. Key 
macroeconomic assumptions in the base case scenario include trend real GDP 
growth of 3% and consumer price inflation near 2% annually over the decade.

Oooo - I love backing up opinions with facts. Read the 8/5 full report for fun:

http://www.standardandpoors.com/ratings/articles/en/us/?assetID=1245316529563