Just found out that my install build server still runs 10.1.5 and that
NSPropertyListSerialization is only available in 10.2. Then I wrongly upgraded the partition named Jaguar, which had a preview of 10.2 installed. Now I am upgrading the right partition named Mac OS X the one with the custom, self-written build system. That takes another 45 min and my last (cheap) train is gone. Next train is in two hours. Sucks....