Apple’s nex gen iphone is said to have fingerprint recognition
The first thing that comes to mind is the ol' ‘unlock device’ scenario. That’s boring. But if the device recognizes independent fingers on the fly, then we can map individual fingers to secure data in the cloud.
eg. Using a friends phone (and your recognized finger) you can call and text using your private address book, the second we detach the data dissolves. You could pull up your favorite songs on the index finger, and store draft documents to your pinky.