By default Virtual Earth is in miles to change to kilometers:
map.SetScaleBarDistanceUnit(VEDistanceUnit.Kilometers);
usage:
map = new VEMap('myMap');
map.LoadMap();
map.SetScaleBarDistanceUnit(VEDistanceUnit.Kilometers);
At the current time this does not effect 3D mode. A bug has been lodged with MS.
search terms: kilometer kms mile distance