[malmazan]

In case I save somebody the time to do the research:

PHP Code:

<vb:if condition="$threadinfo['threadid'] > '1234'"> 


This worked for me on the SHOWTHREAD template out of the box. I have used for the href tag to to keep the Facebook likes on old threads after going from http to https (SSL)

For CMS articles I used:

PHP Code:

<vb:elseif condition="$vbulletin->nodeid < 123" /> 


on the facebook_likebutton template and the vbcms_content_staticpage_page template if you use static pages)