Boxes is free software under the GNU General Public License (GNU GPL), version 2.
The current release is version 1.1.2. For older revisions, feel free to browse the release history.
The boxes sources are now all on GitHub, including previous releases:
For the (historical) record, the source of the outdated version 1.1 is also on metalab (FTP).
The author supports binaries for intel/linux and intel/win32. Boxes has been compiled on a very wide variety of platforms, and for older releases, some of these binaries are available via the release history. If you have binaries for different and/or new platforms, please send them in!
Windows and Linux binary download: https://github.com/ascii-boxes/boxes/releases/latest
According to boxes user Michel, boxes can be installed on MacOS X (32bit) by simply typing
brew install boxes. (Information of October 3, 2012)