Indeed this is still the same in CS5.5. again, it's not per se a bug, just a limitation in how the motion is evaluated. The workaround would be to nest your comp and apply CC Force Motionblur in the parent comp. I tried and this gives the expected result, it may just make rendering very slow.
Thanks for the confirmation. I have a static camera with an animated interest point, will have to think about how to force motion blur. Not in front of it now so will try later.
Seems like a bug to me! I wonder if I can set up the environment in 3d and bring it into AE with baked textures...