If only USPTO.gov site ran on WordPress, that URL might've been a functional permalink!

Automattic is listed as the registrant, which is because they're the original owner of the trademark. But the WordPress Foundation is the last listed owner, meaning they currently own it.

It was transferred a few years ago: http://ma.tt/2010/09/wordpress-trademark/

Edit: This was meant to be a reply to this comment by Jim, must've forgotten to click the correct reply button.