Hi
http://www.muktware.com/bitsnbytes/3027
"Preupgrade provides an upgrade directly to the latest version of
Fedora. It is not necessary to upgrade to intermediate versions. For
example, it is possible to go from Fedora 11 to Fedora 13 directly.
PreUpgrade is stable and is available in all current Fedora releases.
While PreUpgrade downloads the necessary packages, users are free to
continue using their systems. This gives an experience similar to a live
upgrade."
Rahul