I thought I had a rattle coming from the passenger side window and after going for a drive with a service manager he felt that it was also coming from the left side dash vent.
They took it apart and added some anti rattle tape around the vent area and the majority of the noises went away.
I can still hear some noise from the window area however I am wondering if after switching to winter tires - the ride has softened and the noise has dissipated. Will have to wait till spring to see if it returns.
On UK preface lifted 1 series there were a number of problems with poor seals around the door frames on this same side causing the exact same issues that I would hear - Rattling from the window when it was cold. I searched around and found the issue with 3 series too. Here are some links that I saved that talked about fixes.
A 1 series where the dealer fixed the window rattle by changing the door seals.
http://www.babybmw.net/forum/viewtop...2ff2a&start=15
about half way down there is a fix with lubricant by a UK dealer on a 1
http://www.babybmw.net/forum/viewtop...rattle&start=0
perfectly describes problem and mentions the old BMW branded product as a fix.
http://www.e90post.com/forums/showth...=window+rattle
another option used by a dealer in the USA as it sounds like the BMW product is not longer avail in north america
http://www.m5board.com/vbulletin/e39...i-pfledge.html