Knol vs. Wikipedia

Google is challenging Wikipedia with a new service called Knol. Unlike Wikipedia entries, each Knol article will be written and edited by a single author. I suspect that Knol authors will get to share some of Google's advertising revenue.

I was wondering if a Knol author could copy verbatim material on Wikipedia? Could you, for example, take a Wikipedia article, slightly improve it and put it on Knol? Or if you create an Knol article but then see some good material on the parallel article in Wikipedia, could you just add the material to your entry? If so, Wikipedia will be at a competitive disadvantage compared to Knol because I'm certain that Google won't allow others to freely copy Knol's content.