Both Windows Vista and Mac OS X include some sort of desktop widgets. Ubuntu doesn’t by default, but it’s easy to get the same features with Screenlets. Screenlets are written in Python with the Screenlet framework and drawn with vector SVG graphics. This post explains how to install, configure, and use Screenlets on Ubuntu 7.10.
Screenlets require Compiz desktop effects (or another compositing window manager) to be turned on.