Cactus is a simple but powerful static website generator using Python and the Django template system. Cactus also makes it easy to develop locally and deploy your site to S3 directly. It works great for company, portfolio, personal, support websites and blogs.
To get a quick overview watch this short video tutorial.
I developed Cactus because I wanted a standard, easy system that designers at Sofa could use to build and deploy fast websites. So typical users would be designers that are tech-savvy, want to use templates, but don't like to mess with setting up django or S3.
Since then it has evolved quite a bit with a plugin system that supports blogging, spriting, versioning and is extensible.
You can find more discussion about static site generators in this Hacker News discussion.