Doesn't looks like jQuery UI has support for it so you could add it yourself like this:
$.ui.draggable.prototype._mouseStop = function(event) {
    //If we are using droppables, inform the manager about the drop
    var dropped = false;
    if ($.ui.ddmanager && !this.options.dropBehaviour)
     dropped = $.ui.ddmanager.drop(this, event);
    //if a drop comes from outside (a sortable)
    if(this.dropped) {
     dropped = this.dropped;
     this.dropped = false;
    }
    if((this.options.revert == "invalid" && !dropped) || (this.options.revert == "valid" && dropped) || this.options.revert === true || ($.isFunction(this.options.revert) && this.options.revert.call(this.element, dropped))) {
     var self = this;
     self._trigger("reverting", event);
     $(this.helper).animate(this.originalPosition, parseInt(this.options.revertDuration, 10), function() {
      event.reverted = true;
      self._trigger("stop", event);
      self._clear();
     });
    } else {
     this._trigger("stop", event);
     this._clear();
    }
    return false;
}
Would allow you to do this:
$(document).ready(function($) {
    $('#draggable').draggable({
     revert: true,
     reverting: function() {
      console.log('reverted');
     },
     stop: function(event) {
      if (event.reverted) {
       console.log('reverted');
      }
     }
    });
});