Comment 2 for bug 861637

Tested with Ubuntu 12.04:

With Gnome 3, System Load Indicator does not show up in the panel, but instead in the notification area on the bottom right! This is quite useless, because this notification area only appears when the mouse is over it. Furthermore, the notification area seems to allow only one graph to be displayed, and its width must be not too wide (20 pixels is ok, 30 is not). If you try to have a wider display or multiple graphs, then the icon becomes tiny, invisible or messed up.

With Unity, System Load Indicator does not display at all at first, but you can change a panel setting with dconf to make it visible. Then it is working quite fine but needs a lot of CPU time (I will file a new bug report about that).