From Fedora Project Wiki

I would suggest this does not go far enough. KDE is ata point now where its pretty stable and reliable

however functionality changes dramatically during point releases.

We should keep a fedora release on the major version it was released with

so F-13 will have 4.4.x forever. F-14 can get 4.5.X and you can run rawhide if you really must have it. this is really in the best interests of user experience of KDE on fedora.