The same question occurred to me when I watched the announcement. I spent a little time on Google and what I found is very unsettling. The links to Ayers, while not explicit, can easily be inferred.
In addition to his role in Chicago schools, Duncan runs the so-called Ariel Education Initiative, funded by Ariel Capital LLC (the outfit that generated huge amounts of money for the Obama campaign). His sister Sarah, also on the Ariel Education board, is coordinator of the Community Schools Program for the University of Chicago -- where Bill Ayers is happily employed at public expense).
Ariel Capital LLC is like a gigantic octopus with tentacles reaching into every part of Chicago machine politics with direct Daley/Blagojevich connections.
It seems to me that this appointment takes Chicago machine politics national. Here are some links that those who are smarter than me and who have more free time might wish to explore:
There's much, much more, and all of it very disturbing. Google the names of all the Ariel Capital board members. Following the muckety.com links is very "educuational."
It is not the University of Chicago. (Private school, ex home of Milton Friedman, Ed Levi, Leo Strauss and others)