I'm trying to make a map with Google Map API and MarkerClusterer. It's works perfect with a simple JSON file (like this http://google-maps-utility-library-v3.googlecode.com/svn/trunk/markerclusterer/examples/simple_example.html).
But I would use Fusion Tables (simple to edit/add/del markers): http://www.google.com/drive/apps.html#fusiontables.
Is it possible ?
Of course you can. You may request FusionTable-data via the FusionTables-API. This may be done on serverside, but also via AJAX(the API supports JSONP). Once you got the data the workflow will be similar to the JSON-example in your question.