Directories such as /bin, /sbin, /lib, and /lib64 are now being moved to their respective locations within the /usr directory as trying to unify the Fedora file-system. However, as to not break compatibility, symlinks will be in place for redirecting from the old locations. Solaris was actually the first operating system to begin migrating everything into /usr, with the transition having been completed last year with the release of Solaris 11.
The case for merging the entire base operating system within /usr was presented earlier within the Fedora camp, but the actual changes are about to go into effect within Fedora Rawhide for what will become Fedora 17 this May. At the moment for users running Fedora Rawhide and upgrading, some manual steps are needed to change the file-system layout over to the new unified structure. Fedora users wishing to know about the Fedora implementation details and steps to watch out for, read this mailing list announcement.
For those wanting to know why this merge is being done and to clarify what's actually happening, there's this detailed page on FreeDesktop.org that nicely goes over all of the details.
Besides this transition, there's a whole lot of other great features to make Fedora 17 a Beefy Miracle, as it's codenamed.