“We got quite different answers about local area networking (LAN), where both Dustin or Sigaty said they were still discussing it, however, Pardo knew immediately: "we don't have any plans to support LAN," he said and clarified "we will not support it." The only multiplayer available will be on Battle.net.”

http://www.incgamers.com/Interviews/190/StarCraftIIDevelopersInterviewed