Collective.recipe.changelogger is a project mainly written in ..., it's free.
Another David Glick idea implementation
collective.recipe.changelogger is a zc.buildout recipe that takes two KGS files and outputs a changelog.
e.g.
You can use this recipe in your buildout like so::
[changelog]
recipe = collective.recipe.changelogger
prev = http://dist.plone.org/release/4.0.4/versions.cfg
next = http://dist.plone.org/release/4.0.5/versions.cfg