No, it has not been solved as far as I know.
The steering wheel "rattle" is not more common in any circumstance. It simply happens over rough pavement and I do not feel any vibration. I can also make it happen with the car sitting still by simply wiggling the steering wheel back and forth. What's the option code for little gremlins?
1980 450SL @ 103,000 miles
1966 230SL @ Unknown Milage
2006 C230 @ 110,000 miles (Sold)
1994 E420 @ 118,000 miles (Sold)