Download the gnome-packagekit from Updates-Testing and apply it along with the other Packagekit updates and all will be well.
The problem was that they cleared the other updates to Packagekit and didn't include gnome-packagekit.
Jeffrey.
Try sudo yum update --skip-broken
gnome-packagekit has been broken for about 8 hours.
pastebin what you get for:
ls -l /etc/yum.repos.d
grep -i enabled -C 5 /etc/yum.repos.d/*.repo
yum update --skip-broken -y
You are on 10, right? With what did you tinker?