i could spend a lot of time speculating on "what went wrong?" most liberal blogs will probably have posts like that. i won't write a whole lot about my own thoughts because others have already gotten most of the important points. like kristof in the nytimes:
One of the Republican Party's major successes over the last few decades has been to persuade many of the working poor to vote for tax breaks for billionaires. Democrats are still effective on bread-and-butter issues like health care, but they come across in much of America as arrogant and out of touch the moment the discussion shifts to values.
or eric alterman:
They don’t care that Iraq is turning into murderous quicksand and a killing field for our children. They don’t care that the Bush presidency has made us less safe by creating more terrorists, inspiring more anti-American hatred and refusing to engage in the hard work that would be necessary to make a meaningful dent in our myriad vulnerabilities at home. They don’t care that he has mortgaged our children’s future to give trillions to the wealthiest among us. They don’t care that the economy continues to hemorrhage well-paying jobs and replace them with Wal-Mart; that the number without health insurance is over forty million and rising. They don’t care that Medicare premiums are rising to fund the coffers of pharmaceutical companies. They don’t care that the air they breathe and the water they drink is being slowly poisoned and though they call themselves conservatives, they even don’t care that the size of the government and its share of our national income has increased by roughly a quarter in just four years. This is not a world of rational debate and issue preference.
we already knew that large majorities of bush supporters believe things that are clearly false. bush managed to bring these people out to the polls en masse. the "sleeper issue" of the election was "moral issues" (read: hating abortion and hating gays).
but from what i've read so far, i think kos had the best advice: remember goldwater.