Views Slideshow, show alternating content types
In broad strokes, you could use Views' views_pre_render() hook to reorder the result of the View, eg...

function YOURMODULE_views_pre_render(&amp;$view) {

   switch ($view-&gt;name) {

      case 'NAME_OF_YOUR_SLIDESHOW_VIEW':

        // to figure out what you have to work with, take out when done debugging
        drupal_set_message('&lt;pre&gt;' . print_r($view-&gt;result, TRUE) . '&lt;/pre&gt;');  

        // and here are the broad strokes... cycle through $view-&gt;result and
        // grab all the "rows" and re-order them by whatever business logic
        // you need, in this case even or them by content type instead of whatever
        // logic it is sorted in originally.  it you then set $view-&gt;result to this
        // new order, it will then be rendered by the Slideshow in that order

        break;

      // other Views might go here

   }

   // other code might go here, too...

}