I was looking at my version of Mecurial and I don't understand how it is that it can be Copyrighted and Free software at the same time.
Mercurial Distributed SCM (version 1.3.1+7cea12e70129)
Copyright (C) 2005-2009 Matt Mackall and others This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
All software, even free software, is copyrighted. The free software license just means that the copyright holder is granting you rights to use, modify, and distribute the software under certain specific terms. The reason they are allowed to do this in the first place is because they are the copyright holder and thus get to dictate the usage terms of the software.
In fact, this idea is what was so novel about the GPL in the first place: it used the framework of copyright law to enforce distribution terms for software covered by the license.