I was wondering that while I was typing. I thought I saw something on a tweet earlier today mentioning MAC address information. I couldn't locate my source (and even if I could - it's twitter), so that's why I surrounded it with a "maybe". See - conditional language that completely absolves me of any wrongdoing, perceived or implied!
Even so, jpeg pictures tied to jpeg EXIF data tied to accounts tied to the front and back of driving licenses. Oops...