I have that too on my '08, now that you mentioned me. It doesn't do it all the time though. For the life of me, I have no freaking idea what the hell it could be. It sounds like if we had a cable-driven speedometer; remember those?
First time I hear of that noise from somebody ehse, so glat I'm not the only one. But the car is so damn noisy, it quickly gets drown out by road noise, so it doesn't bother me that much anymore.