This is from someone who had a "squeaker"... From what I hear the newer 8800s are coming out with something under the rails to keep them quiet. If you search "squeaky sides" you will gets lots of rants, comments and ultimately solutions. At the end of the day for me the rail issue was the first and only time I have questioned the build quality of a RIM product. I currently do not have tape or dental floss in my 8800 and I am squeak-free. Yes, if I apply an inordinate amount of pressure I can get the sides to make some noise...but almost any phone would under the same circumstances.
I am very happy with my 8800 and it does feel hefty and solid. One thing that has really surprised me is the screen and how much it has not gotten scratched. I prefer going unprotected as it just looks and feels better (

) and my 8800 has no significant scratches. In fact, the only minor scratch it has is about 4mm long and the screen has to be clean, tilted in the light at a perfect angle to see. Basically, only the most hardcore of OCD would have an issue with it. I have used Plexus on my 8800 and I highly recommend that product.
Anyways, very happy with the build quality of my 8800.