petebarnett

<?php

template_preprocess_node(&$vars) {

    $field_name = 'your_entityreference_field';
    $nid = $vars['content'][$field_name]['#items'][0]['target_id'];

    // Add a flag to the referenced node for theming
    $vars['content'][$field_name][0]['node'][$nid]['#node']->some_arbitrary_flag = 'some arbitrary value';