Facebook OpenID Selector
From the libraries/openid-selector/README.txt:


  
  how to plug-in facebook provider
  put the following code in providers_large or providers_small:
  


facebook = {
     name: 'Facebook',
     url: "javascript:facebook_click();"
}



  where facebook_click is something like:


function facebook_click() {
      $('#&lt;id of html fbconnect element&gt;').click();
}



  the same mechanism also applies if you want to plug-in any oauth or xauth provider


So that is what the README says. I specifically had to do the following I'm using Drupal7.8 with openid-selector module 7.x-3.x (2011 May 07):

In modules/openid_selector/openid_selector_fb.js:
Replace the chunks that look like similar with the ones Ive posted.

providers_large.facebook = {
  name: 'Facebook',
  url: "javascript: $('.fb_button').click();"
};


and again for this chunk

Drupal.behaviors.openid_selector_fb = { attach: function (context) {
  $('.fb_user-login-button-wrapper').hide();
}}