BitTorrent Sync: Secure File Sync Between Computers Using P2P Technology [Public Alpha]

BitTorrent Sync, a free to use (but not open source) tool that can be used to automatically synchronize files between computers using the BitTorrent protocol, is now available for all as public alpha. The application runs on Linux, Windows, Mac OS X and NAS.
The tool, which has been in closed alpha for the past four months, is advertised as "a simple tool that applies p2p protocol for direct live folder sync with maximum security, network speed and storage capacity".