Hi there, 
I am running  Joomla 2.5.11 and VM 2.0.20
As I haven't find a working solution to this problem with these specs, here is my small contribution to all the help I received.
Please consider I am not a professionnal and this should be validated by senior developper.
But I works pretty fine and looks coherent to me.
This is what I did : 
1. Create an override of the virtuemart component in your template 
yoursite\templates\yourtemplate\html\com_virtuemart\productdetails
2. In product details replace the existing code in
yoursite\templates\yourtemplate\html\com_virtuemart\productdetails\default_manufacturer.php file
<div class="manufacturer">
....
</div>
with this one
<div class="manufacturer">
    <?php
    $link = JRoute::_('index.php?option=com_virtuemart&view=category&virtuemart_category_id=' . $this->category->virtuemart_category_id.'category&virtuemart_manufacturer_id=' . $this->product->virtuemart_manufacturer_id );
    $text = $this->product->mf_name;
    /* Avoid JavaScript on PDF Output */
    if (strtolower(JRequest::getWord('output')) == "pdf") {
   echo JHTML::_('link', $link, $text);
    } else {
   ?>
        <span class="bold"><?php echo JText::_('COM_VIRTUEMART_PRODUCT_DETAILS_MANUFACTURER_LBL') ?></span><a href="<?php echo $link ?>"><?php echo $text ?></a>
    <?PHP } ?>
</div>
Hope this will help and give feedback if it works for you :-)
Best,
Christophe
			
			
			
				I tried this, it only brought up a pop up of the manufacturer's details page....did it work for you?
			
			
			
				Any success with forum search on this? Some attempts maybe?
Be more precious about your version also - http://forum.virtuemart.net/index.php?topic=79799