CentOS 6 comes with Upstart to replace the aging Sysv init startup mechanism. 
The various deamons on Centos will migrate to Upstart gradually. It is advisable to use Upstart in this case since CentOS 6.
Previous versions of Centos will require to install it, just like Ubuntu before Edgy release (2006), but the RPM is made for CentOS 6.