The ATrpms repository provides many bleeding edge software packages so if you have a development server where you install new apps this repo can be very useful. The instructions are not 100% clear about how to install this repository on CentOS Linux which would also be the same on RedHat Linux but not on Fedora Linux. Anyhow the example used on the ATrpms site relates to Fedora so the repo file needs to be modified to work on CentOS as noted below.
Installing the EPEL repository on CentOS Linux is easy to do so the below is simply a reference point if needed by anyone. EPEL stands for Extra Packages for Enterprise Linux and is a community based repository that was created for add-on Fedora Linux packages. There are many cases where installation instructions assume that the EPEL repo is already installed so if you run into an error because of a missing package or dependency package the EPEL repository is a great place to start. Below I have listed the i386(32-bit) and x86_64(64-bit) EPEL repository package list links which will allow you to easily verify that the packages you need are available before installing the EPEL repository. After the EPEL repository package list links there are separate commands listed to install the EPEL repository on 32-bit CentOS Linux 5.X and to install the EPEL repository on 64-bit CentOS Linux 5.X.