Koha

Koha is an open source integrated library system. First developed in New Zealand in 2000, Koha is now used by libraries around the world and has been contributed to by over 150 developers.
Koha is a 100% web-based system where both the staff an patron functionality is accessible via the browser. It comes complete with modules for circulation, patron management, cataloging, serials, acquisitions, reporting and and extensive administrative menu for customizing the system to your library's needs.
Releases for Koha
Providers
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Consulting, Custom Development, Hosting, Training
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Consulting, Custom Development, Hosting, Training
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Consulting, Custom Development, Hosting, Training
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Consulting, Custom Development, Hosting, Training
Upcoming Events for the Koha Package
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Koha 3.8 Demo
19-Jun-2012 -
KohaCon12 Hackfest
9-Jun-2012 to 11-Jun-2012 -
KohaCon12
5-Jun-2012 to 7-Jun-2012 -
Koha Users Group - Wellington, New Zealand
18-May-2012 -
Koha 3.8 Demo
15-May-2012 -
Koha 3.8 Demo
10-May-2012 -
2012 European Koha Hackfest
19-Mar-2012 to 23-Mar-2012

The Conversation
License
Koha is actually licensed under GPLv2 or later
I've added the specific GPL
I've added the specific GPL licenses to the taxonomy. Is Koha really GPLv2 or GPLv3?
Its GPLv2 or later .. to wit
Its GPLv2 or later .. to wit
# Koha is free software; you can redistribute it and/or modify it under the
# terms of the GNU General Public License as published by the Free Software
# Foundation; either version 2 of the License, or (at your option) any later
# version.
Ah, right!
I forgot about that clause...thanks for pointing it out.