Joomla! has one significant drawback, the print preview is actually duplicated content of the real article.
Also the PDF files generated from com_content, as well as the send to friend pages are useless for indexing from the search engines and should be avoided. Every SEO specialist will tell you that.
I am suggesting to Joomlart to change the overwrrite of an article, so the PDF buttons, e-mail to friend button and print button contain the nofollow attribute.
You can do it by changing the:
/templates/YOUR_TEMPLATE/html/com_content/article/default.php
(if you use these icons in category blog and section blog views, you will need to make the changes there as well)
<?php echo JHTML::_('icon.email', $this->article, $this->params, $this->access); ?>
to
<?php echo JHTML::_('icon.email', $this->article, $this->params, $this->access,array('rel'=>'nofollow')); ?>
—————-
<?php echo JHTML::_('icon.print_popup', $this->article, $this->params, $this->access); ?>
to
<?php echo JHTML::_('icon.print_popup', $this->article, $this->params, $this->access,array('rel'=>'nofollow')); ?>
——————
<?php echo JHTML::_('icon.pdf', $this->article, $this->params, $this->access); ?>
to
<?php echo JHTML::_('icon.pdf', $this->article, $this->params, $this->access,array('rel'=>'nofollow')); ?>
I suggest to Joomlart to make these changes in the base theme in the T3 plugin as well.