I wrote part of a FAQ last November, and if you're interested in the breakdown of GCC, GLibC and kernel adoption since Red Hat Linux 4.0, you'll want to read this: http://www.geocities.com/thebs413/RH-Distribution-FAQ-3.html

I've been loosely working on a "Linux Configuration Management" book covering Red Hat distributions since. I might update this FAQ if I have time, although my priorities have been elsewhere as of late.