Source : Free On-Line Dictionary of Computing

Birds Of a Feather
     
        (BOF) (From the saying "Birds of a feather flock together") An
        informal discussion group, scheduled on a conference program
        or formed ad hoc, to consider a specific issue or subject.  It
        is not clear where or when this term originated, but it is now
        associated with the {USENIX} conferences for {Unix} techies
        and was already established there by 1984.  It was used
        earlier than that at {DECUS} conferences and is reported to
        have been common at {SHARE} meetings as far back as the early
        1960s.
     
        (1994-10-11)