DIVORCE & KIDS: How much do they really need to know?

DIVORCE & KIDS: HOW MUCH DO THEY REALLY NEED TO KNOW? I briefly skimmed this article in the New York Times today and it seems this author got a lot of flak for telling her children that she sometimes thought about getting a divorce from their father. http://parenting.blogs.nytimes.com/2010/10/27/telling-your-children-too-much/?scp=3&sq=divorce&st=cse
How much should children be told about divorce, I wonder? And when should they be briefed on this situation? I would love to hear what folks think is appropriate in this situation. And does it matter how old the children are?