After fixing a problem with berserko mail on Sunday (the ORDB.org spam blacklist started blocking everything), I found this little news nugget:
3/26/08 Update: ORDB has “listed the entire world” – returning any query with a “listed” response. The result is that if you still have ORDB in your mail server config files, you’re now blocking 100% of your inbound mail. For anyone still trying to “use” ORDB, you’re not going to receive any inbound mail until you disable queries to it.