Right now, the only overlay is the Loading service.
http://ionicframework.com/docs/angularjs/views/loading/
Right now, the Loading service is pretty limited in functionality. It’s not very customizable. However, there are a few Issues and Pull Requests asking for improvements.
The overlay you link to it more like a pop-up or dialog than the Ionic Loading indicator. There are a few requests in for this feature already.
In the meantime, you may what to consider using the native dialog service via PhoneGap.