They fixed it, btw www.paulphusion.de was still pointing to his old address at 81.169.145.158. I don't know what he did, but it seems that he didn't follow what posterous suggested (adding an A record to its domain pointing at posterous). Sadly i wasn't quick enough to collect more data about posterous.com...
Waiting for the official post, i'd say that Paul misconfigured something that they didn't test for that particular input.