ATM it works, players can't destroy fences, fire can't burn it but, if a TNT explode, fence will be destroyed, and the fire seems to be eternal (if you punch fire, it will disappear) on the fence without burning it.. Oo I put a permission node to let admins/op(if no Permissions) destroy fences. I can submit it now and try to do some things later tonight or tomorrow
Well, after some issues with github, it's submit: http://forums.bukkit.org/threads/sec-mech-invinciblefences-v0-1-953.24436/