Generating a Changelog with Git - ShellJS Recipes - http://shelljs-recipes.tumblr.com/

shelljs-changelog-git.js

// dependencies: a git repo, git tag release versioning
function generateChangeLog(lastRelease, nextRelease) {
  echo('Generating Changelog from ' + lastRelease + ' to ' + nextRelease);
  
  ('## ' + nextRelease + '\n').to('CHANGELOG.tmp');
  exec('git log ' + lastRelease + '...' + nextRelease + ' --pretty=format:"+ \`%h\` - %s" >> CHANGELOG.tmp');

  cat("CHANGELOG.tmp", "CHANGELOG.md").to("CHANGELOG.new.md");
  mv("CHANGELOG.md", "CHANGELOG.old.md");
  mv("CHANGELOG.new.md", "CHANGELOG.md");
  rm("CHANGELOG.tmp");
  rm("CHANGELOG.old.md");
}