QR codes can also come in handy for publishing offline announcements or advertising. Perhaps I'll take advantage of this and tell people about my blog using flyers around town.
On Twitter, @TroyJMorris and @knakao have been going back and forth lately about the topic of QR codes. I do not see an easy way to link to the back and forth tweets. Maybe thats a what uniquely named hash tags are for. Dont'w know if QR codes are so geeky that they'll likely take off into the main stream, but its a decent try especially with the way smart phones and other portable devices are becoming ubiquitous.
Both android and iPhone have good apps for scanning QR codes and taking an appropriate action. Got the iPhone, I have started using an app named, Scan.