As of 2010-12-02, Fedora 12 has reached its end of life for updates and support. No further updates, including security updates, will be available for Fedora 12. Fedora 13 will continue to receive updates until approximately one month after the release of Fedora 15.  The maintenance schedule of Fedora releases is documented on the Fedora Project wiki:

https://fedoraproject.org/wiki/Fedora_Release_Life_Cycle#Maintenance_Schedule

This is a bell to me that I have to upgrade to Fedora 14, I usually stick with a Fedora release for a year or two releases as I spend a considerable amount of time tweaking the system and never look at it again until it reaches its EOL. I do wish that Fedora had a longer gaps between each releases but this has already been discussed extensively on the mailing lists. Fedora aims to to bring bleeding edge software/technology to the community this is one of the reasons why the gaps between each releases are so short. Some bug fixes and features take up to two years to appear in enterprise products so I can’t really complain. If like me you are still running on anything else prior to Fedora 13 it is high time to upgrade and take advantage of the best the community has to offer.