From Fedora Project Wiki
Fedora 11 added many development improvements, enhancements in automation, a step improvement in virtualization, and greatly enhanced security. If you just can't wait to see what Fedora 12 will have to offer, you can now get a peek at:
http://fedoraproject.org/get-prerelease
Of course, this is a beta release, so there might be things not quite right. Should you trip across one of them, be sure it gets fixed before release by reporting your discovery at: