This first test release of the next version of Fedora Linux, codenamed the Spherical Cow, as declared "GOLD" today during a team meeting. Fedora 18 Alpha will now officially be released next Tuesday, 18 September.
"Thanks to everyone who helped to make it possible, to ship Spherical Cow out of the doors to the wild journey for Beta and GA!" The announcement can be found on the Fedora mailing list.
If you haven't yet read up on the Spherical Cow, see the top features for Fedora 18. Fedora 18 final should be released in November barring anymore delays in the release process.