Just as an FYI (not sure if this is related to anyone else's issues), after updating to the most recent bazaar, I had to select the USPS shipping methods again. They had been turned ON before the update; after the update, I had to revert the Workflow_ng configurations to their defaults as well as re-activate the USPS shipping methods. Oddly enough, my USPS webtools API number / username was still intact, as were all of my shipping method preferences (First Class Parcel, etc.). Weird.