From Fedora Project Wiki

Comments/Questions lists the final release date as February 6, 2009 now. Does the XFCE team feel confident that they can get this release into Fedora after the Alpha has been released and before Beta?

Yes, it may not be that 4.6 final is out in time, but if so, we can update after release. In my testing 4.6b3 is pretty stable, and I would at least expect rc's before Beta time. - kevin