http://www.bukkit.fr/index.php?/topic/9468-un-point-de-spawn-temporaire-dans-un-monde-diff%C3%A9rent/

plugin.yml

name: SpawnUtils
version: 1.1
author: NeatMonster
main: fr.neatmonster.spawnutils.SpawnUtils
commands:
  spawnutils:
    aliases: [su]

SpawnUtils.java

package fr.neatmonster.spawnutils;

import org.bukkit.Bukkit;
import org.bukkit.ChatColor;
import org.bukkit.Location;
import org.bukkit.command.Command;
import org.bukkit.command.CommandSender;
import org.bukkit.entity.Player;
import org.bukkit.event.EventHandler;
import org.bukkit.event.EventPriority;
import org.bukkit.event.Listener;
import org.bukkit.event.player.PlayerRespawnEvent;
import org.bukkit.metadata.FixedMetadataValue;
import org.bukkit.plugin.java.JavaPlugin;

public class SpawnUtils extends JavaPlugin implements Listener {

    @Override
    public boolean onCommand(final CommandSender sender, final Command command, final String label, final String[] args) {
        if (command.getName().equalsIgnoreCase("spawnutils")) {
            if (sender instanceof Player)
                sender.sendMessage(ChatColor.RED + "This command isn't for players!");
            else if (args.length != 1 && args.length != 4 && args.length != 6)
                sender.sendMessage(ChatColor.YELLOW + "Usage: /su <player> [x] [y] [z] [yaw] [pitch]");
            else {
                final Player player = Bukkit.getPlayer(args[0]);
                if (player == null)
                    sender.sendMessage(ChatColor.RED + "This given player doesn't exist!");
                else if (args.length == 1) {
                    player.removeMetadata("spawnutils", this);
                    sender.sendMessage(ChatColor.GREEN + "Spawning location unset!");
                } else
                    try {
                        final int x = Integer.parseInt(args[1]);
                        final int y = Integer.parseInt(args[2]);
                        final int z = Integer.parseInt(args[3]);
                        final int yaw = args.length == 6 ? Integer.parseInt(args[4]) : 0;
                        final int pitch = args.length == 6 ? Integer.parseInt(args[5]) : 0;
                        player.setMetadata("spawnutils", new FixedMetadataValue(this, new Location(player.getWorld(),
                                x, y, z, yaw, pitch)));
                        sender.sendMessage(ChatColor.GREEN + "Spawning location set!");
                    } catch (final Exception e) {
                        sender.sendMessage(ChatColor.YELLOW + "Usage: /su <player> [x] [y] [z] [yaw] [pitch]");
                    }
            }
            return true;
        }
        return false;
    }

    @Override
    public void onEnable() {
        getServer().getPluginManager().registerEvents(this, this);
    }

    @EventHandler(priority = EventPriority.MONITOR)
    public void onPlayerRespawn(final PlayerRespawnEvent event) {
        if (event.getPlayer().hasMetadata("spawnutils"))
            event.setRespawnLocation((Location) event.getPlayer().getMetadata("spawnutils").get(0).value());
    }
}