I was brave today and decided to install 6.1.92 (Raw Hide 20000228) on my secondary workstation as an upgrade. When I tried to compile several KDE programs it gave me an error "iostream.h missing". This file is in egcs-c++ under Red Hat 6.1, but has been moved to libstdc++-devel in the 6.1.92 distribution of Red Hat. Most software won't compile without this package being installed. I installed it manually, and everything else worked fine for me.
The package libctdc++-devel is not installed by default, as most users do not comopile programs.