What went wrong with the exit polls in the 2004 election? They were predicting a Kerry victory, yet when the official results came in, Bush won in most of the key swing states. Some early attempts at explanation:
The polling organization put out a report analyzing the reasons for the discrepancies on election day. Read it here.
The official site for the polling organization itself here.
An academic piece by Steven Freeman at the University of Pennsylvania here.
To see exit poll results by race, age, gender, etc., try CNN
A group trying to get access to the workings of voting machines so that elections can be transparent here