PearlNerf is a plugin for Bukkit which is used to nerf the capabilities of ender pearls in order to allow for fairer combat on PVP servers.
You can find stable downloads with detailed changelog information in the files section of the plugin's BukkitDev page.
Simply drop the latest .jar into the /plugins directory of your server.
Further plugin information can be found at the plugin's BukkitDev page.