How to generate such beautiful changelogs

I currently work in a corporate environment where we use SVN and JIRA to manage our code, bugs and development tasks.

I've always been fascinated at how beautiful the changelogs of the best open source projects are compared to the 'release notes' we prepare for our clients using Microsoft Word.

Example: http://rspec.info/rails/changes-rspec-rails.html

The clarity of what's happening is refreshing.

How are such changelogs generated? What are the tools and processes that a team needs to have in place to generate such changelogs.

Thanks for taking time to share.