gistfile1.js

var klass = "_jetpackNotification";
jetpack.tabs.onReady(function(doc){
  $("body",doc).append('<div id="'+klass+'" style="position: fixed; bottom: 0; right: 0; height: 0; width: 151px;"><div style="height: 40px; width: 150px; background: #ddd; border: #999 solid; border-width: 1px 0 0 1px"></div></div>');
});

function notify(options) {
  var doc = jetpack.tabs.focused.contentDocument;
  $("#"+klass+" div", doc).text(options.body).parent().animate({"height":41},"slow", function(){
    setTimeout(function(el){$(el).animate({"height":0},"slow")},3000,this);
  });
}

// instead of jetpack.notifications.show(), call notify() with the same argument