apex:param inside knowledge:articlelist

I appear to be having issues with apex:param being used inside the knowledge:articlelist component. I was wondering if anyone had experienced similar issues or possibly (hopefully) knew a fix.

Here is my VF:

<ul>
    <knowledge:articleList articleVar="article" articleTypes="{!articletype}" sortBy="mostViewed" pageSize="10"> 
            <li>
                <apex:outputLink value="{!URLFOR($Action.KnowledgeArticle.View, article.id,['popup' = 'true'])}" target="_blank">
                      {!article.title}
                     <apex:param name="articleid" value="{!article.id}" assignto="{!articleid}"/>
                </apex:outputLink>            
            </li>
    </knowledge:articleList>
</ul>

The links never set the parameter. I set up a commandbutton to do some debugging and the parameter is always null.

Thanks for your help, Ross

Edit: After reading I felt like I needed to clarify I'm using a custom controller and have set the param assignto variable as public with a getter and setter.

Edit 2: To debug I just created a commandbutton to call a simple method that uses the system.debug.

Public void debugthis(){ system.debug('Article ID is: ' + articleid); }