How to Share Music Wirelessly by Tapping Two Android Devices Together

Android users are probably already familiar with the doubleTwist Player (free) from doubleTwist, available on the Android Market. They recently added AirPlay support for users with AirSync ($4.99) that allows streaming to Apple TV and DLNA devices, which is sure to provoke some cease and desist requests from Apple. But their second, newly unveiled feature is more enticing—doubleTap, which adds proximity-based file sharing for Android devices.
What does that mean?
doubleTap lets you wirelessly transfer videos and songs just by tapping two Android smartphones together that have the doubleTwist app installed.
The catch?
They must be devices with NFC (Near Field Communication) integrated, which Android 2.3 Gingerbread supports, though only one notable device has shipped with NFC built-in—Samsung's Google Nexus S. But Google predicts that between 40 and 100 million NFC-enabled phones will ship out this year, including the Samsung Galaxy S due for a May 26th release date.
How does it work?
NFC initiates the file sharing, with the actual file transfer happening over Bluetooth or Wi-Fi. Check out the official demo unveiled at Google I/O 2011 to see it in action: