Many readers have sent this story. Unfortunately, I'm quite busy today, but I will try to say more next week. Very briefly, it's clear that this is an attempt to harass Professor Cronon and probably constitutes an abuse of process; it's much less clear that it violates academic freedom, though it arguably impinges upon Professor Cronon's First Amendment rights. It calls to mind the events at UVA, which were successfully challenged last year. (That case involved a climate scientist's e-mail relating to his research, which is why it was quite clearly an academic freedom issue. Professor Cronon, by contrast, is writing about issues outside his area of academic research.) There's also a statutory interpretation issue about the meaning of "private" e-mails under the Wisconsin FOIA. I'll open comments for more links and information, and I will try to weigh in with more substantive analysis by Monday. Comments will take awhile to appear, so please only submit once. Thanks.
UPDATE: This is informative as to Wisconsin law governing FOIA requests.