Yeah, I'd been thinking "Magento" from about halfway into that article.

Wordpress uses the EAV db pattern too (have a look at the wp_options and wp_meta tables).

Of course, Magento and Wordpress use it in fundamentally different ways - so this project I've got to build a combined search across a site with both Magento (EAV for products) and Wordpress (non-EAV for posts/pages) in use, is in that "it'll sit on the backburner until it becomes critical or somebody else solves it for me first" state…

Squiz's Matrix (open-source CMS) also uses an EAV model.