Papaya is a mobile application that magics your phone book into a social-communication tool. You import your phonebook into Papaya and you see your friends appear as soon as they register too. Then you can send free text messages through the existing Instant Messaging programs (Live Messenger, ICQ, QQ, etc), chat and play games. Furthermore you can choose your own avatar. Papaya is available in Java for 'normal' mobile phones, the iPhone and Android will soon follow.
Future vision by Erwin van Lun
You take your friends list everywhere. Currently you have to copy it, but later you’ll indicate who you are, which social networks you’re on and your friends will appear automatically and you can call them with a press of a button, text them, IM them, play games, whatever. And when you meet a new friend you add them to your mobile and they’ll be available on another mobile or tv or wristwatch too. This’ll need a little more time, but not much longer.