I happen to be one of the folks who has also had no luck getting 3 different dealerships to find any TSB on the clutch chatter. I also called Mazda customer service and they did not find anything regarding a service bulletin either. I took a copy of the TSB to the dealer and they dismissed it as well.
I also have had problems reproducing the chatter when I took it to the dealer, primarily because it tends to be intermittent. On some days it chatters everytime I take off, but other days it doesn't do it much, if at all.
This is my first Mazda. Although I cant argue with how fun this car is to drive, it has generally made a poor showing in some basic areas (clutch chatter, grindy shifting when cold, cold engine rattle, broken CD player, leaking oil cap on valve cover, soft engine mounts). Unfortunately, all the running around I've done trying to solve this clutch problem (unsuccessfully) has only convinced me to not get another Mazda. It doesn't make sense that on a year old car, I'm essentially being forced by Mazda to spend close to 1000 bucks on replacing the clutch and flywheel.