I can't see how content distributed under the licenses Knol offers can be reproduced in WMF projects, and I can't see how content produced under WMF's licensing options can be reproduced in Knol. To me, that raises a serious problem.
Could you explain that? My understanding was that something released under CC-BY could be used pretty much anywhere as long as it's appropriately attributed. We attribute all content on Wikipedia, so why can't we use it? (The other direction obviously can't be done, there's no dispute there, as far as I can see.)