http://web.blogads.com/blog/wp-content/plugins/twitter-blackbird-pie/js/blackbirdpie.js?ver=20110404

1(function() {
2  var intentRegex = /twitter\.com(\:\d{2,4})?\/intent\/(\w+)/,
3      shortIntents = { tweet: true, retweet:true, favorite:true },
4      windowOptions = 'scrollbars=yes,resizable=yes,toolbar=no,location=yes',
5      winHeight = screen.height,
6      winWidth = screen.width;
7
8  function handleIntent(e) {
9    e = e || window.event;
10    var target = e.target || e.srcElement,
11        m, width, height, left, top;
12
13    while (target && target.nodeName.toLowerCase() !== 'a') {
14      target = target.parentNode;
15    }
16
17    if (target && target.nodeName.toLowerCase() === 'a' && target.href) {
18      m = target.href.match(intentRegex);
19      if (m) {
20        width = 550;
21        height = (m[2] in shortIntents) ? 420 : 560;
22
23        left = Math.round((winWidth / 2) - (width / 2));
24        top = 0;
25
26        if (winHeight > height) {
27          top = Math.round((winHeight / 2) - (height / 2));
28        }
29
30        window.open(target.href, 'intent', windowOptions + ',width=' + width + ',height=' + height + ',left=' + left + ',top=' + top);
31        e.returnValue = false;
32        e.preventDefault && e.preventDefault();
33      }
34    }
35  }
36
37  if (document.addEventListener) {
38    document.addEventListener('click', handleIntent, false);
39  } else if (document.attachEvent) {
40    document.attachEvent('onclick', handleIntent);
41  }
42}());