I'm not sure I like this example code.  Hiding the personaSSO implementation is a benefit to this approach. Is it being exposed to allow changing which parts of the DOM this stuff points to? 

If so, I think more detail should be added to this part of the readme to clarify.  

That or throw in some random example code ala:

```javascript
...
config = {
  target: ...,
  onlogin: function( topic, data ) {
    if ( topic === "monkey" ) {
      alert("banana");
      return;
    }

    alert("Not banana");
  } 
}
```