First off, I think this is super cool. It's a novel and interesting take on a very boring but necessary concept, and he's taken the time to get the design looking nice as well -- he could easily have just soldered an attiny to a USB connector, and that wouldn't have had the same charm.<p>Secondly, it seems the security implications are very slightly more severe than one might think. The card only activates when you press caps lock three times. This means it must be able to receive key presses, as well as to send them. From my understanding of his description, keyboard HID devices which support the boot protocol profile also receive notification of key presses (<a href="http://frank.circleofcurrent.com/cache/usbbusinesscard_details.htm" rel="nofollow">http://frank.circleofcurrent.com/cache/usbbusinesscard_detai...</a> and search 'boot protocol'). So in theory this could record everything you typed, as well as do destructive things to your computer. And of course storage is not an issue as it's likely that the host is connected to the Internet.<p>It seems borderline paranoid to think like this w.r.t. someone's business card, though.