The Jargon File (version 4.4.7, 29 Dec 2003):

Borg
 n.

    In Star Trek: The Next Generation the Borg is a species of cyborg that
    ruthlessly seeks to incorporate all sentient life into itself; their slogan
    is ?You will be assimilated. Resistance is futile.? In hacker parlance, the
    Borg is usually Microsoft, which is thought to be trying just as
    ruthlessly to assimilate all computers and the entire Internet to itself
    (there is a widely circulated image of Bill Gates as a Borg). Being forced
    to use Windows or NT is often referred to as being ?Borged?. Interestingly,
    the Halloween Documents reveal that this jargon is live within Microsoft
    itself. See also Evil Empire, Internet Exploiter.

    Other companies, notably Intel and UUNet, have also occasionally been
    equated to the Borg. In IETF circles, where direct pressure from Microsoft
    is not a daily reality, the Borg is sometimes Cisco. This usage
    commemorates their tendency to pay any price to hire talent away from their
    competitors. In fact, at the Spring 1997 IETF, a large number of ex-Cisco
    employees, all former members of Routing Geeks, showed up with t-shirts
    printed with ?Recovering Borg?.