A Typekit snippet that uses Modernizr.load (yepnope) to asynchronously load webfonts only for in browsers that support @font-face.

modernizr-typekit

Modernizr.load([{
  test: Modernizr.fontface,
  complete: function() {
    TypekitConfig = {
      kitId: 'xxxxxxx',
      scriptTimeout: 3000
    };
    (function() {
      var t = setTimeout(function() {
      }, TypekitConfig.scriptTimeout);
      var tk = document.createElement('script');
      tk.src = '//use.typekit.com/' + TypekitConfig.kitId + '.js';
      tk.onload = tk.onreadystatechange = function() {
        var rs = this.readyState;
        if (rs && rs != 'complete' && rs != 'loaded') return;
        clearTimeout(t);
        try { Typekit.load(TypekitConfig); } catch (e) {}
      };
      var s = document.getElementsByTagName('script')[0];
      s.parentNode.insertBefore(tk, s);
    })();
  }
}]);

Modernizr.load [
  test: Modernizr.fontface
  complete: ->
    TypekitConfig =
      kitId: "xxxxxxx"
      scriptTimeout: 3000
    (->
      t = setTimeout(->
      , TypekitConfig.scriptTimeout)
      tk = document.createElement("script")
      tk.src = "//use.typekit.com/" + TypekitConfig.kitId + ".js"
      tk.onload = tk.onreadystatechange = ->
        rs = @readyState
        return  if rs and rs isnt "complete" and rs isnt "loaded"
        clearTimeout t
        try
          Typekit.load TypekitConfig
        return

      s = document.getElementsByTagName("script")[0]
      s.parentNode.insertBefore tk, s
      return
    )()
    return
]