Hi PK and Madisn,
Could you add support for custom post types, please.
The "Custom Post Type UI (http://webdevstudios.com/support/wordpress-plugins/)" plug-in is very popular and very compatible with a whole range of other plug-ins.
Could you extend the current list of "Supported Post Types" listed in the "Visible at: Pages, Posts, Frontpage" to also dynamically list registered Post Types and Taxonomies.
When this plugin is determining if it should show then there would be additional post types available to match against and therefore show the scroll-triggered-box.
For Example: A website is developed with 3 custom post types; news, product and customer. This would allow your plug-in to show the scroll-triggered-box on "product" pages.
Thanks for considering the feature enhancement,