One problem related to air bag on-off switch has been reported for the 2008 Mini Cooper. The most recently reported issues are listed below.
Air bag malfunction light went on and stayed on. It did go off when a passenger sat in the seat. Sensor switch had to be replaced, a costly job. Seat was replaced. The only way I recognized the error was when there was no passenger. I feel that if I always drove with a passenger I would not have known of the malfunction. This problem is not unknown to the manufacturer as it has been discussed on websites and when mentioned to non Mini repair shops, they were aware of it.