I guess he uses his iPhone
<a href="http://www.cnet.com/news/knock-knock-app-unlocks-mac-with-two-thumps-on-your-iphone/" rel="nofollow">http://www.cnet.com/news/knock-knock-app-unlocks-mac-with-tw...</a>
I'd like to see more info on how this was accomplished. I just tried it on my mac, but couldn't get it to bypass the unlock screen. Is there any sort of unlock app running on that mac?