The Fine Free File Command (FFFC)

http://www.darwinsys.com/file/

The home page for the 'file' command.

http://freshmeat.net/projects/file/

Talks about updates.

http://en.wikipedia.org/wiki/File_(Unix)

Give a nice history of the 'file' command.

 ftp://ftp.astron.com/pub/file/

An ftp link to the latest source code.

http://directory.fsf.org/project/file/

The Free Software Foundation (FSF) page.  A bit old.  The most recent version is said to be 4.23.

http://mx.gw.com/pipermail/file/2010/000534.html

Notes on the file-5.04 release.