So, we're still running Leopard Server because I'm waiting for any snow leopard issues to get ironed out before I upgrade. We were about to put our internal podcast into use when I noticed Podcast Producer forgot how to talk to the Xgrid controller. After spending some time staring to the settings, I finally realized that the Xgrid Controller setting had to be set to the same domain as the Kerberos domain, which in my case is improperly set to Server.local instead of the server's actual name.

So, for future reference: The xgrid controller address is tied to the kerberos domain.