Democracy Corps, the polling firm of Stan Greenberg and Roberg Shrum, has just released an extensive analysis of the Dem victory, and it concludes that the election represented a watershed meltdown for the conservativism which has been dominant since 1994:

2006 was a meltdown election -- the meltdown of the Gingrich-Bush conservative model for politics and governance -- that gave Democrats control of both the House and Senate and a large majority of the governorships and state legislatures...

On November 7th, the American people voted not just against Republicans; they voted against their model for governance that got them bogged down in war, aligned with corrupt, special interests rather than people, and unable to govern competently on important issues.

Democracy Corps' full analysis here.