Do these actually need to be `null` or would `undefined` work for the API? Because if `undefined` does, this could be simplified down to:

```
track : function (event, properties) {
  properties || (properties = {});

  var personEvent = {
    name : event,
    target_id: properties.target_id,
    note : properties.note
  };

  window._lnq.push(['_logEvents', personEvent, properties]);
}
```

Also note that you can't assume properties is an object, it might be `undefined` so trying to access a property on it will error.

Just a random thing I spotted, I'm sure @calvinfo will give this a once-over too.

Cheers