How are there later versions of minecraft servers than bukkit releases?

I see this all the time. A new version of minecraft would be released then servers would update within a week EVEN THOUGH bukkit was still on an older version… And all their plugins are updated with it. How can i do this with my server? I have bukkit 1.7.9 but was wondering how to update it to 1.7.10 and update my plugins along with it. I think it has something to do with allowing players in with early versions but how do i do that?

There really isn't a bukkit server 1.7.9 yet. Because people on 1.7.2 can join those servers. The reason why bukkit isn't updated is because bukkit has to match all the code with the current update so it can take some time. The reason why plugins are updated is because dev builds are easy to use that bukkit