Source : Free On-Line Dictionary of Computing

Share and enjoy!
     
        1. Commonly found at the end of software release announcements
        and {README file}s, this phrase indicates allegiance to the
        hacker ethic of free information sharing (see {hacker ethic}).
     
        2. The motto of the Sirius Cybernetics Corporation (the
        ultimate gaggle of incompetent {suit}s) in Douglas Adams's
        "Hitch Hiker's Guide to the Galaxy".  The irony of using this
        as a cultural recognition signal appeals to {freeware}
        hackers.
     
        [{Jargon File}]