I ordered my 13" (4 RAM, 256 Flash) hours after the keynote. I noticed the creaking as others have reported on this list. I had it on the left palm rest. The sound is similar to one made by stepping on a loose floorboard. It did seem as if the bottom panel was flexing. I went to the Genius Bar to see if they could tighten the bottom panel. Instead, they suggested that I return it since I'd had it less than a month. I received the replacement. I have not heard the creaking (fingers crossed). Overall, this one 'feels' more solid. The most odd difference is the feel of the aluminum case. The original always felt strange against the skin of my palms and fingers. I know, I'm probably just sensitive. But, the replacement feels smoother. In any case, I just thought this might help others. I've always learned so much from others' posts.