Hi Todd,
Is there some replacement for the package updater?
As fas as I know, puplet is the systray applet for pup. Pup had been the update / package
manager before it got replaced by PackageKit.
Unfortunately, there's no known notification applet in PackageKit, at least not in my
knowledge base.
In case of Xfce, you could use a little script that uses xfce4-notify to show on-screen
notification or the panel plugin xfce4-genmon-plugin that calls the script periodically.
$ yum install xfce4-genmon-plugin
See also
http://goodies.xfce.org/projects/panel-plugins/xfce4-genmon-plugin