A high-level introduction to Plone and its features, for those new to Plone.
Community-maintained manual for the Plone content management system.
The central place for discussions, questions and community communication.
The curriculum used for Plone training classes, including tutorials and walk-through examples; very useful as a self-guided learning resource.
The Plone community adheres to extensive testing while developing software, and uses Continuous Integration. Here you can find the latest test runs, managed by Jenkins.
Plone is fully open source, and is free software under the GPLv2. On GitHub.com, you can find the many repositories that make up the Plone project, ranging from the core software itself to the documentation sources.
The annual Plone conference is held in cities around the world and includes training classes, keynotes, presentations, demos, and sprints. Videos and slides are posted to the conference web site.
This site aggregates Plone-related blogs from around the web.