What is morality?

I am not a philosopher, but I think this is a fascinating question to explore. I'd like to point you all to a post by Christian blogger Ken Brown, in which he explores the implications of an interventionist god who does not prevent all evils.

We had such a vigorous discussion in the comments that he made a second post to further explore the difference between theistic and atheistic approaches to morality and the problems of evil.

Please read the comments there and participate if you are so inclined. My question for you, my dear readers, is what you think the nature of morality is?

Ken sees moral codes as truth claims: if something is good, that is a fact about the world, in something like the way that gravity or the structure of the atom are facts. So, is a claim like "Murder is bad" something that can be true or false in an objective sense?

I see moral codes as personal choices - sometimes (nearly) universal, but nevertheless inherently subjective. I follow Hume in seeing "is" and "ought" statements as inherently separate types of statements. Is a claim like "murder is bad" more of a preference than a fact?

This divide is not simply a theist-atheist divide: I know atheists who would agree with Ken that morality has an objective basis external to us, and I suspect that there are theists who do not. What do you think? How do you understand morality?