Today, Google I/O launched doubleTap, its update to the doubleTwist Android app, that allows mobile phone users to trade music by simply tapping their devices together. They seem pretty excited about it, but the Bump app from Apple, which has been around for years and lets iPhone users exchange personal info directly into their phones by fist-pumping each other, is an activity not only fun and seemingly magical, but also a little sexy. The free exchange of music, however, we suspect is illegal. The two apps are demonstrated at top.