(moved to Alpha-Beta)
Fedora maintains the current and previous releases until the month after the next release. So, assuming a six-month release cycle and this schedule for Fedora 9: http://fedoraproject.org/wiki/Releases/9/Schedule
(which will probably push into May, in reality) then you'd see Fedora 8 reach EOL sometime around the first of next year. Even so, you'll still have some repositories maintaining packages a bit beyond that and if you've just plain fallen in love with Fedora 8, then you can keep it and just watch for security updates or important packages. There are still Fedora 1 and 2 machines limping along....
Here's a News item that explains it: http://forums.fedoraforum.org/showthread.php?t=158081