SFO controllers are known to make some late runway changes for the arriving aircraft. The two runways are very close together to the sidestep maneuver required is not too drastic but it is still not necessarily something the crews want to deal with. A Southwest 737 was on approach and passing near us on the shore when it apparently got the change instructions. We got a sudden topside view as it turned towards us followed by a reversal of bank as it straightened up on the new runway. Compared to the average arrival, this was quite a bit of excitement! Also, if you look closely, you can see another Southwest jet in the background that had just departed.