It looks like the Galactic Coordinate System (which, sensibly but to the confusion of the casual reader is centered on the Sun) is also 'backwards' with respect to the right hand rule. The galactic north pole is actually the galactic rotational south pole. This seems to be because the coordinate system was based on the rotational direction of the Sun.

I think I may have just exceeded my recommended daily nerdallowance of reading about spinning things in the sky.