Xfce 4.10 was released to the world 2012-04-28 and Fedora rawhide was updated in the days right after that. (Thanks Christoph!)
Our Fedora 18 feature has been approved: https://fedoraproject.org/wiki/Features/Xfce-4.10
My side repo for existing Fedora releases has been updated also to 4.10 final, and I have also built for Fedora 16 as well now. See:
http://repos.fedorapeople.org/repos/kevin/xfce-4.10 for a repo file for your /etc/yum.conf.d/ directory.
Lots of nice new little bugfixes and additions in Xfce 4.10. Give it a try today.