I just picked up my new GTI MKVI manual this afternoon and, without knowing about this problem, heard the rattling sound within the first hour of driving. I find it most easily reproducible in 3rd and 4th at low revs.
So when I got home I immediately googled it and found this thread. Like a lot of other people on here I find it really annoying. It may not be very loud, but when I first heard it I was like wtf!?!? My first reaction was "Someone has fanged the **** out of this car and caused it to 'ping'", something you usually only hear in crappy old cars. I'm pretty sure this isn't the desired reaction VW would like from a first time driver of one of their cars.
After reading through most of the posts I reckon the best thing to do would be to start up an online petition on a site like this:
iPetitions: Start a free online petition / Create a petition
Then get everyone on here with the same problem to sign it and also hit up the other VW forums for more signatures. Then email it to the most appropriate VW representative. Seems like the most constructive thing we could do, rather than individually going into dealerships and recreating the issue only to be told "it's a characteristic of the car", which is by the way the biggest load of **** I've ever heard.