Talabrek's Ultimate SkyBlock plugin continually updated.
The original plugin can be found over at http://dev.bukkit.org/bukkit-plugins/ultimate-skyblock/
This is used by Frostcast and contains many bug fixes. This may or may not contain all of the features of the original plugin. All commits found here are tested before being pushed and are suitable to run on a production environment.
A compiled jar can be found at http://ci.frostcast.net/job/uSkyBlock/