As soon as that mod updates to 1.3.2 or 1.4.2 (not sure what version it is right now) It is multiplayer compatible. All mods 1.3.2+ are multiplayer compatible because of the way minecraft now runs a server so you can open it to LAN (So basically all singleplayer worlds are just servers with 1 person on it unless you open it to LAN)
Herobrine 1.4.2 server mod?