The PackageKit source tree needed gtk, libnotify and all sorts of weird gnomey libs to compile, which seemed to upset the non-GNOME people a little. The actual daemon just needs glib, libnm, dbus-glib and policykit so it did seem somewhat non-optimal to me as well. I've split the daemon and GUI parts into two projects:
git clone git://people.freedesktop.org/~hughsient/PackageKit git clone git://people.freedesktop.org/~hughsient/gnome-packagekit
Just install gnome-packagekit when you have PackageKit installed – gnome-packagekit uses libpackagekit to do all the heavy lifting, so the GUI bits are actually very simple:
[hughsie@hughsie-laptop src]$ wc -l *.c *.h 56 pk-application.h 725 pk-application.c 104 pk-application-main.c 60 pk-notify.h 958 pk-notify.c 76 pk-update-icon.c 1979 total
In the gnome-packagekit project I'll start marking strings translatable, and there's also a yelp file for someone to fill out for me in the future. I might move gnome-packagekit to GNOME svn when things are a bit more stable, so stuff like translations and HIG changes are easy to commit. This means it's really trivial to port an existing applications to use libpackagekit, or to create, for example, kpackagekit.