So after a few small iterations, I've installed a heavily modified
version of the CVS `log_accum' script to compact multiple-directory
commits into one message.  Among other changes, my version handles
branches.

A hypothetical example of the new output would look like:

  From: Charles M. Hannum <mycroft@netbsd.org>
  Subject: CVS commit: src
  To: source-changes@netbsd.org
  Reply-To: mycroft@netbsd.org

  Module Name:    src
  Committed By:   mycroft
  Date:           Sat Aug  8 02:32:05 UTC 1998

  Modified Files:
	  src/bin/bar: Makefile bar.c
  Added Files:
	  src/usr.bin/foo: Makefile
	  src/usr.bin/foo [tag1]: foo.c yow.c
	  src/usr,bin/foo/include: foo.h
	  src/usr.sbin/qux: qux.c
  Removed Files:
	  src/sbin/baz [tag2]: baz.c
  Log Message:
  This is a test.  This is only a test.

I've gotten a couple of suggestions that I may act on later:

* Change the `module name' (and the subject) to be the largest common
  prefix of all the directory names; e.g. so that a commit of multiple
  files in pkgsrc/mail/fetchmail would be labeled as
  `pkgsrc/mail/fetchmail' rather than just `pkgsrc'.

* Include RCS version numbers somewhere (probably after the
  traditional output, at the end of the message).