gistfile1.js

var sockets = [...] ; // some array of sockets

for(var i = 0; i < sockets.length; i++){
  socket.on( 'CardPick', function(data) {
    Draft.cardPick( data, draftId, socket );
    // `socket` will always be the last item in `sockets` every time the callback is called on any of the sockets
  });
}

for(var i = 0; i < sockets.length; i++){
  (function(socket){
    socket.on( 'CardPick', function(data) {
      Draft.cardPick( data, draftId, socket );
      // `socket` will now be what we expect it to be.
    });
  })(socket);
}