Just installed and ran their server - there's a demo site built in. Looks neat, but I'm not sure how secure it is. Saw a demo of their qr code-reading mobile auth app earlier this year that looked interesting.
Couldn't someone snap my qr code whilst I wasn't looking and have access to my account on their phone? I think there's some interesting uses of qr codes for authentication, but I'm not sure this is one of them.
I'm starting to think this is a really great idea - to have somewhere to keep a private personal history - particularly for checking in to keep a track of where I've been without appearing to be a self-important moron. You know who you are FB friends!