Packagekit-python-console is a project mainly written in Python, it's free.
Example source code using PackageKit GI gobject-introspection from Python
Example source code using Python GI bindings for PackageKit
Please see: http://www.packagekit.org/gtk-doc/
Also, to get the latest gir in ubuntu, check: https://launchpad.net/~ximion/+archive/packagekit