It makes sense there's an app that replaces the practice of exchanging business cards. According to this LA Times article one of those app's is called Bump. I downloaded the app to my iPhone and hope to use it at a conference next week.
Back in 2008 I attended a conference that used a technology called nTag. Each attendee was issued an nTag device that acted as their confernece badge. You could use it to exchange business contact information, receive conference messages and updates, request presentations, and participate electronically in polls conducted by presenters. It was pretty cool. Four years later that technology may no longer be relevant. How long before I look at my iPhone and say 'this thing is so 2012'?