Image upload callback in new 3.5 media

There is a FileUploaded event being fired in wp-includes/js/plupload/wp-plupload.js.

Alternatively (and propably the better way) you may want extend wp.Uploader with your own success callback .

(function($){

    $.extend( wp.Uploader.prototype, {
        success : function( file_attachment ){
            console.log( file_attachment );
        }
    });
})(jQuery);