For a recommendation to ESRI, add the option to add a kml to a ArcGIS Online Map. That would be one powerful tool that could throw Google for a loop! It would come under the add layers tool, I think it gives you options to ArcGIS Online, The Web, or ArcGIS Server. I would add kml layer to this list.
You can create a javascript service that will view both data on a ArcGIS Server, and kml layers. look at the extending ArcGIS Javascript for Google Maps API. It is a combination of the API's.
For a recommendation to ESRI, add the option to add a kml to a ArcGIS Online Map. That would be one powerful tool that could throw Google for a loop! It would come under the add layers tool, I think it gives you options to ArcGIS Online, The Web, or ArcGIS Server. I would add kml layer to this list.