Bukkit

• Fix for fill and trim commands not working on newer 1.2+ worlds due to new region file type.
• Fix for potential problems caused by player location changing while border checking task is referencing it.
• Update "new location" method to accept locations at Y positions higher than the old 128 limit; vertical limit is now based on Bukkit's reported World.getMaxHeight() value.
• Fix for chunk mapping method used by fill command not properly closing region files when finished with them, leading to leftover open file references.

This is not a problem with WorldBorder, but CraftBukkit 1.2 dev builds might have some world generation problems which they've yet to address. Remember that if you're running a CraftBukkit 1.2 dev build, it's just that; it's not a stable recommended release build.