The official Petals documentation is available at http://doc.petalslink.com. You can access it any time thanks to the navigation bar located on top of the page (common through all the Petals web sites).
Tutorials and Training
If you want to get a quick start on Petals and are on the self-learning side, we propose a quick-start tutorial to grasp the basics concepts and use of Petals ESB, based on Petals ESB 3.1: get started on Petals ESB in five lessons.
White Papers and News
If you want to learn more about SOA and ESB, we recommend browsing these sources: