It's important to note that it's built as a separate plugin that requires the Aptana Studio 3 from 2010-08-18 to work properly. Aptana Studio 3 can be grabbed at: http://aptana.com/products/studio3/download
This version provides syntax highlight (using the Aptana Themes)

The highlighted tokens are the ones defined in the templates in the "Django tags" context (so, tags to be highlighted can be added or removed).

Also, there's code completion based on templates for the django-templates related stuff and pretty nice html completions inherited from the Aptana html editor.
The image below shows the html completions, a django-templates template completion and its result and a django-templates template completion for the filters.

That's it for now. Please grab it and let me know if it's working or if there's a bug lying around there so that it can be fixed before the official release :)