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ChangeLogs
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Changelogs have an interesting relation to version control systems.
They are, for some projects, the primary way of examining history.
They provide a pattern and standard for writing commit history, which
may encourage people to enter more details (function names, etc) in a
systematic way than they otherwise might.  The ChangeLog is available
offline, in tarfiles, or even when the project has been switched into
a different VCS.

GNU ChangeLog format is only the most important, not the only such
file.  Debian uses a different format for packages.  At a higher
level, 

At the same time the information there is some redundancy: both the
ChangeLog and the VCS want to hold the description of what has been
done, including descriptive text, names of files changed, etc.

Some people say__ that ChangeLogs are mostly needed because of the
limitations of CVS (and originally RCS): if it was easy to read the VC
history when disconnected and at local speed, and if there are atomic
commits then they might be needed rather less.

__ http://gcc.gnu.org/ml/gcc/2004-06/msg00270.html

There should be hooks called to create the log message template and
before committing it.  These might, for example, populate it with
space for per-file comments, or check that it is in the right format.