"Reboot required" package updating from command line?

How can I tell if a package I'm about to update requires a reboot for it to be inplemented?  (RHEL 5.8)  From the Software Updater GUI interface, there is an icon to the left that shows which updates do.  I want to see that requirement when I use 'yum' or 'rpm' from the command line.  Even after I update a package that I know requires a reboot, nowhere does it say that.  Do I just not know where to look?  Or maybe I'm missing an option??  Thanks for any pointers!  ...Marie Hutchens

Marie Hutchens