Since Redhat stopped supporting their commercially available Linux distribution, they moved to an Enterprise Linux Server (RHEL) and left everyone else to use a community effort (Fedora Core). Considering the cost of RHEL, the source packages were recompiled and redistributed. The resulting CentOS is a free binary compatible distribution of RHEL without the proprietary Redhat only software. I have seen some virtual private servers using CentOS for the virtualized operating system.
I played around configuring different installs of Apache, MySQL and PHP. I tried recompiling source RPMs (
SRC.RPM) from FC4, but it became tricky to have multiple versions running. I will try again from source files instead.
My opinion so far is that it is a VERY stable and usable server distribution. If the software it included was newer I would probably be using it as my main Linux desktop. Anyways, more later as I learn more.