I have studied the new Nav Menu Management in WP 3.
Many of the other links in WP can use
wp_rel_nofollow_callback. But it seems that the new nav menu cannot.
Therefore, how is it possible to create a function to inject an attribute. Specifically, I am trying to work out how a theme functions.php might inject
rel="nofollow" into a link generated by the 'wp_get_nav_menu'_item.