Yesterday, on the 18th of March, the Gnome developers have released Gnome PackageKit 3.8 RC, which is a testing version.
This Gnome PackageKit version fixes some bugs. Gnome PackageKit 3.8 RC is available in a lot of languages, like: Brazilian, Portuguese, Catalan, Czech, Danish, Estonian, German, Greek, Huncarian, Indonesian, Korean, Latvian, Lithuanian, Malayalam, Norwegian Bokmal, Polish, Russian, Serbian, Slovak, Slovenian, Spanish and others.
I will also provide you the download link for Gnome PackageKit 3.6.2, which is a stable version:
Gnome PackageKit 3.6.2:
$ wget http://ftp.gnome.org/pub/GNOME/sources/gnome-packagekit/3.6/gnome-packagekit-3.6.2.tar.xz
Gnome PackageKit 3.7.92:
$ wget http://ftp.acc.umu.se/pub/GNOME/sources/gnome-packagekit/3.7/gnome-packagekit-3.7.92.tar.xz