[CentOS-virt] Package updates and "required" reboots

Fri May 6 13:45:31 UTC 2011
Ben M. <centos at rivint.com>

I still operate under the assumption that glibc and kernel updates "require" a 
reboot to be prudent on a Linux OS.

With CentOS Xen 5.6 (standard installation, SELinux enabled) is there an FAQ or 
general user consensus as to when to do a reboot after what updates?