"Screenlets, like gDesklets, can be installed through
Add/Remove if your on Intrepid. If your still using Hardy Heron, it
is still in the repositories, but you have to go to Synaptic. To
make it start up when you boot, launch Screenlets from either
Applications > Accessories > Screenlets (usually Intrepid) or
System > Preferences > Screenlets (usually Hardy), then check
the box saying "Auto start on login." From this same window, you
can add the widgets that come with Screenlets."