I figured i'd pass on the info I gained while removing the trim on my new 07 GT M3.
The trunk is the only place with holes through the metal, the mazda pops off with 3 pins holding it on. The center mazda symbol on the trunk has two alignment pins as well as double sided tape - if removed I suggest cutting the tape when pulling it off, or pull gently so the plastic doesn't get bent - since you have to put it back to fill the alignment holes.
The side molding, the "2.3" engine size and the "3" on the trunk are all adhesive tape. The side molding I started at the 'pointed' side and pulled with multiple fingernails - started peeling right off - by far the easiest section to remove. All tape on the car comes off cleanly, you may have some stuck behind if it's not a hot day out, but you can push it with your finger and get it to roll off with no residue. Well, there was a strip under 1mm wide on the drivers rear door, so I went over that and all other locations with alcohol to clean before re-washing and waxing.
Once I did this and rinsed off the dirt crap that was behind the moldings, then rewaxed, there's no trace of where any decals were - worked very well. My car color is black, it was about 72F outside and sunny, vehicle built in feb, delivered in april, moldings removed in june. I dunno if removing them earlier or later has much effect on the adhesion quality or not.

Hope this is useful info.