xhtml 2.0 question

Looking through the link module,
http://www.w3.org/TR/2003/WD-xhtml2-20030131/mod-link.html#s_linkmodule,
it says "Authors may use the link element to provide a variety of
information to search engines..." giving some examples of alternate
links. Does anyone know of any search engine, spiders etc. that makes
use of this info?