I didn't re-read this entire thread before posting this so my apologies if its a repost but check out this thread from 7-series over on bimmerfest
http://www.bimmerfest.com/forums/sho...d.php?t=487021
I have this issue on my 11/26/10 build 550i as well. I have not yet been in for service for this yet as its mostly just an annoyance in my car - maybe not as intense as some of you are experiencing. But its definitely there and its definitely not right.