Randfish over at SEO Chat posted a thread named SEOmoz.org - In Google's Sandbox - Hilarity Ensues! In that thread he describes how his SEOmoz.org blog has been sandboxed after moving it from socengine.com/seo to seomoz.org.
Randfish describes that for searches he used to rank well for, he no longer ranks for. He gives many examples in the thread and describes that he has never done any "unnatural" link building for this site.
I applaud Randish for giving this a go. He said towards the end of the thread, "I'm just glad I was able to do this with a site that doesn't need SE traffic..." This is in response to Ben's advice for most people, that he "rarely if ever advise anyone to mess around with already well ranked pages unless they have too."
One thing is not clear from the thread is when this all occurred. I'll assume he didn't move over the domain name within a week or so. :)