matawikipe.js

// ==UserScript==
// @name      mata wikipedia yonderu
// @include   http://*.wikipedia.org/wiki/*
// @include   http://twitter.com/public_timeline?from=userjs
// ==/UserScript==

(function() {
  if (location.href.indexOf('wikipedia.org')>0) {
    var wikipe = function() {
      var object = document.createElement('object');
      object.id = 'matawikipe';
      object.style = 'visibility:hidden;position:fixed;height:1px;width:1px;top:0;left:0;';
      setTimeout(
        function() {
          object.addEventListener('load',
          function() {
            object.contentWindow.postMessage(encodeURIComponent([
              '「'+document.title.replace(/ - Wikipedia.*?$/,'')+'」', 
              location.href
            ].join(' ')), '*');
          },false);
          object.data = 'http://twitter.com/public_timeline?from=userjs';
        }
      ,180000);
      document.body.appendChild(object);
    }
    document.addEventListener('load', wikipe, false);
  } else if (location.host == 'twitter.com') {
    document.addEventListener('message',
      function(e) {
        if (e.domain.indexOf('wikipedia.org')<0 ) return;
        var url = 'http://twitter.com/statuses/update.json';
        var x = new XMLHttpRequest();
        x.open('POST', url, true);
        x.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
        x.send('status=またWikipedia読んでる。' + e.data);
      },
    false);
  }
})()

What exactly does this script do?