Fedora contributors were able to vote for a narrowed down list of codenames for one week, at which point I mentioned Fedora 18 might be a Frankfurter or Spherical Cow. Sure enough, Spherical Cow was the most popular codename. The narrowed down list of codenames and their rank were Spherical Cow (1359 votes), Halva (1087), Chamoy (1072), Tandoori Chicken (964), Frankfurter (930), Pop Soda (821), and Ketchy Ketchup (536).
Spherical Cow is another arguably weird codename that succeeds the Beefy Miracle, a.k.a. Fedora 17. It's still being decided whether future Fedora releases will carry a codename or not, and if so, whether it will still be left up to community members for proposals.
The Fedora 18 Spherical Cow codename announcement was made this morning on the Fedora announce list.