...

var Server = Pusher.new('api_key', 'channel');

// option 1

Server.bind('event',function(data){
    console.log("data received");
});

/* option 2
   Re Build your element
 */

Server.bind('event',function(data){
    var strong = $("<strong>",{
      text: data.user.name
    }),

    link = $("<a>",{
      href:"#"
    });

    link.append(strong);
    $("#box_"+data.app.name+"_app_"+data.name).html(link);
  });

/* Option 3
   Build on request.
 */

Server.bind('event',function(data){
    $(data.tag).html(data.html);
  });

...