Pidgin code without an explicit copyright is covered by the following
copyright:

  Copyright (C) 1999 Eric Kidd. All Rights Reserved.

  Permission is hereby granted, free of charge, to any person obtaining a
  copy of this software and associated documentation files (the
  "Software"), to deal in the Software without restriction, including
  without limitation the rights to use, copy, modify, merge, publish,
  distribute, sublicense, and/or sell copies of the Software, and to permit
  persons to whom the Software is furnished to do so, subject to the
  following conditions:

  The above copyright notice and this permission notice shall be included
  in all copies or substantial portions of the Software.

  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
  NO EVENT SHALL THE XFREE86 PROJECT BE LIABLE FOR ANY CLAIM, DAMAGES OR
  OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  OTHER DEALINGS IN THE SOFTWARE.

  Except as contained in this notice, the name of the author(s) shall not
  be used in advertising or otherwise to promote the sale, use or other
  dealings in this Software without prior written authorization from the
  author(s).

Other parts of Pidgin originated in Melange, a similar tool written by the
Gwydion Group at CMU. That code bears the following license:

  Copyright (c) 1995, 1996, 1997  Carnegie Mellon University
  All rights reserved.
  
  Use and copying of this software and preparation of derivative
  works based on this software are permitted, including commercial
  use, provided that the following conditions are observed:
  
  1. This copyright notice must be retained in full on any copies
     and on appropriate parts of any derivative works.
  2. Documentation (paper or online) accompanying any system that
     incorporates this software, or any part of it, must acknowledge
     the contribution of the Gwydion Project at Carnegie Mellon
     University, and the Gwydion Dylan Maintainers.
  
  This software is made available "as is".  Neither the authors nor
  Carnegie Mellon University make any warranty about the software,
  its performance, or its conformity to any specification.
  
  Bug reports should be sent to <gd-bugs@gwydiondylan.org>; questions,
  comments and suggestions are welcome at <gd-hackers@gwydiondylan.org>.
  Also, see http://www.gwydiondylan.org/ for updates and documentation. 

I have been informed of CMU's intent to rerelease Melange into the public
domain along with the rest of Gwydion Dylan and Gwydion Sheets.

These licenses permit the use of Pidgin in proprietary and GPL'd
applications. However, if you enhance Pidgin, I request (but do not
require) that you contribute some or all of your changes to the public
under the first copyright in this file.