Sam Harris has had a few things to say on this theme recently.
He argued that "Science can answer Moral Questions" in a talk he gave on the TED forum for Technology, Entertainment and Design.
This has been inevitably criticised by those who, following David Hume, maintain that an "ought" cannot be derived from an "is". Though personally I think Hume was more subtle on this point than those who have adopted his slogan.
Harris has followed up on the criticisms received in "Moral Confusion in the Name of Science" on his Project Reason site.