It appears that we all have the same issue at different levels (i.e. mild/medium to pretty bad shaking) regardless of the engine type (4T, or V6). I am sure you and other customer service reps in this forum heard about all of these by now through private messages.
At this point, I'd kindly request you guys to reach out to someone in GM/Cadillac who can help us instead of telling us 'this is normal' which is ridicules. Most importantly, few people here got some sort of ECM update which apparently got this problem fixed. Can we get details of those so we can go to our respective dealers and guide them to get our car fixed? Last but not least, please do some research to find out the status of the TSBs below (i.e. could possibly be 'the' problem we all experience) and let us know what needs to be done or at least tell us when we can expect a fix if there is no fix yet.
BTW: These TSB's list these problems as 'intermittent' but that is not true, I can reproduce it every day especially when the engine is cool at start in the morning and while stopped at light every single time!
PS: Like I said on the earlier post, I really love this car... the driving experience is so awesome ... If Cadillac can address this problem soon before it ruins the car, it certainly can claim to be the 'car of the year'