When you go to the developer site it states: gksu is being replaced by PolicyKit, please take a look at http://live.gnome.org/gksu (link dead; see https://wiki.gnome.org/Attic/gksu ). It says there ...

gksu

gksu is a library and application used to ask the user for passwords
to run programs as root. It is not a good option now that we have
PolicyKit. Still, we still have applications which are not written to
take advantage of the PolicyKit framework, and since making
applications use it usually involves structural changes, a new version
of gksu will provide functionality similar to the one provided by the
current gksu to cover applications which still haven't been patched to
use PolicyKit. The new gksu will use PolicyKit as backend, instead of
su and sudo. This page intends to work as a notebook for
planning/designing that new version.

Show me the code

Code is being written, and you can fetch it by using git:

$ git clone git://git.debian.org/~kov/gksu-polkit.git/

General Architecture

The new gksu will be composed of three parts:

• an activable dbus system service able to run programs as root or other users, using PolicyKit to enforce policy


• a library providing a simple API that talks to this service an application that is client of the above library, and allows people to


• run programs in a way similar to the one they are able to do with current gksu

So if you want the newest version use the above.

Otherwise check Ubuntu software center, open up Universe, update the sources and you can install it from either USC...

... or from command line with

sudo apt-get install gksu