The suspend/hibernate menu entries in the "System" menu of the Gnome panel are linked to the Gnome Power Manager. If the Gnome Power Manager supports "suspend" or "hibernate", then the corresponding options will show in the menu.
You might have noticed that the suspend and hibernation function in ubuntu/kubuntu won’t work. While there’s no official fix, you might find this work around helpful.
In continued testing on my macbook it appears that I have suspend working solidly. If you enjoy this feature you may want to look into this tutorial. I have never really used suspend/hibernate much in the past because it has been buggy, but now that it appears to be working well I think I may give it a try.