Just did about 200 miles today and the shimmy is definitely getting worse. The repair (see attached invoice for parts/labor info.) done by the regional service manager and engineer was the only thing that minimized the shimmy. After my last conversation with SOA - I am waiting for a check and then I'll be taking it in again ASAP when the next "fix" is made available.
I have not heard definitively if there is a TSB for this issue as of yet, but if you go into the dealer, have them pull up this post and grab the scans of the work done that I included.
To all that have PM'd me - other than the receipt and the conversations noted with the tech and engineer - I don't, unfortunately, have any more info. to share. Between the busings and the e-balancing of the tires using the road-force method, there was improvement - but then it came back - although not as bad as it was at it's worst.
Hope this helps - if YOU have the shimmy - please, please, please bring your car in - it will help us all.