Adam Lasnik of Google fame responded to a thread at the Google Groups for Webmasters today. The information regadarding the -30 day penalty is limited, but his response does add some new information. The reinclussion request, which is only available now when logged into your webmaster tools, is not just for RE-INCLUDING in the index, but also for your site to be re-evaluated if you feel it has suffered some sort of ranking penalty. He has made reference earlier, also noted in the same thread, that an automatic ranking penalty, short of fully deindexing a site, does exist.
Nice find John. It's good to hear (somewhat) definitively that there is a -30 place penalty in existence, and that there is some hope once problems have been cleared up. I would definitely recommend that one make fully certain that they are caught by this penalty before hitting the re-inclusion form, as unnecessary requests may cause further problems - or if not completely cleaned up, perhaps invoke the penalty. The key is it can be used for re-evaluation... but doing so, and when, should be a careful decision. That thread (and ones linked from it) only reinforces what I have been trying to communicate of late - configurations and quality do matter. Duplicate titles, cannonical problems, and 302 redirects are enough to trigger this penalty.