From Fedora Project Wiki
Lifecycle and Maintenance of Fedora
The Fedora Project maintains any given release X until one month after the release of X+2.
This means:
- Fedora 8 will be maintained until 1 month after the release of Fedora 10.
- Fedora 9 will be maintained until 1 month after the release of Fedora 11.
In practice, Fedora releases a new version about every 6 months, which means than each version of Fedora gets updates for about 13 months. This allows users to "skip a release" while still being able to always have a system that is under maintenance. If this is not suitable for you, you might want to take a look at Red Hat Enterprise Linux which is a commercial derivative of Fedora or one of it's free rebuilds.
You can find information on the project releases at Fedora Release Schedule .