From Gallup, a snapshot of American political discontent:
Changes among political independents appear to be the main reason the percentage of conservatives has increased nationally over the past year: the 35% of independents describing their views as conservative in 2009 is up from 29% in 2008.
The data that goes into this comes from 16 national polls conducted between January and September 2009. Findings indicate that the country is getting more conservative across a wide array of issues, including a sense the government is regulating business too much, that global warming is exaggerated, and (boo!) that the government should promote "traditional values" rather than be neutral.
This data is broadly consistent with the Harris Poll, which has shown for the past 30-plus years that self-identified independents and conservatives far outnumber self-identified liberals. Interestingly, this is independent of party affiliation, which has consistenly been more Democratic than Republican.