Watching this made me a bit sick. It sounded more like a Ku Klux Klan rally rather than a comic doing stand-up at a comedy club.
I don't know how or if he will ever be able to live that down or what... but it's deplorable that he talked that way regardless of what the heckler did.
Michael Richard's apology seemed sincere but felt rather weak or lacking in thought, at least to me.
Sinbad gives a good interview about this incident that makes a lot of sense and I think it is worth putting up on this post as well:
When you cross the line from comedy (in whatever form it is given) to hate and anger and racism... well that's when you've gone from funny to dummy.