Mailing the story:
How long will FreeBSD 7.3-release be supported? Two years
FreeBSD 7.3-release has a two-year support life with the option to upgrade to the FreeBSD 8.x branch at any time. More than one -release branch going at the same time? More than one -stable branch, plus a -current branch in constant development? FreeBSD has a whole lot of flexibility depending on what you want out of the system, what your comfort level is with bleeding-edge software, how often you want to update your software, and of course what your hardware and tasks require.