How to roll back packages on CentOS 5 / RHEL 5

CentOS 5 / RHEL 5 preferably uses yum as the program to update, install and remove packages.
When you’ve installed/updates packages with yum or rpm, you can quite easily roll back the updates/installations using rpm.
For this, yum and rpm need to save roll back information, which they do not do by default.
To enable the roll back feature, do the following:

Add tsflags=repackage to /etc/yum.conf.
Add %_repackage_all_erasures 1 to /etc/rpm/macros. If /etc/rpm/macros does not exist, just create it.

You can now install, erase and update packages with yum and/or rpm, and they will save roll back information.

When you want to roll back, use rpm to do so.
You do this by specifying the --rollback switch and a date/time, like the examples below:

rpm -Uhv --rollback '19:00'
rpm -Uhv --rollback '8 hours ago'
rpm -Uhv --rollback 'december 31'
rpm -Uhv --rollback 'yesterday'

Source: http://www.vincentverhagen.nl/2007/12/10/how-to-roll-back-packages-on-centos-5-rhel-5/