Jokes and Racism?

Is there a point where a joke goes too far, when, even thought it was supposed to be just a joke, it is truly racist, or do people take racist jokes too seriously? With the recent controversy over Don Imus, people have been preaching on and on about racism. Isn't a joke just supposed to be a joke, and wouldn't all races be better off if they learned to laugh at themselves? Or does emphasis on a race's flaws change stereotypes, make it worse? Thoughts and opinions only, I dont need to be chastised on my "ignorance".