g1smd - 8:25 am on Sep 3, 2011 (gmt 0)
A few lines of code can detect what page the user requested and then decide to show or not show the button.
I recently did this for the FaceBook "like" button on a MediaWiki-driven website. It should be equally simple to deploy on any script-driven site just as long as you know the URL format for all pages that should display the button or for all pages that should not display the button.
In this case the rule was "don't show the button on pages where URL contains index.php or begins Talk: or...". Additionally, we don't bother showing the button if it is a searchengine bot requesting the page.