1. A medical device system, comprising: a storage device to store current posture state data describing a posture state in which a patient has previously been classified; a sensor to sense one or more signals indicative of at least one of a posture and an activity state of the patient; and control logic to process the one or more signals in a selectable manner that is based on the current posture state data, and to classify a patient as being in a posture state indicated by the processed one or more signals.