I just bumped into the Sun BluePrints Wiki and I think it is worth a visit. It is a companion to the BluePrints Blog and part of the move towards Self-Published Content at Sun, which increases agility and responsiveness to user's needs.
The Recent Content page lists chronologically the latest changes. The more recent entries are created in Wiki format, while the earlier ones are PDF attachments.
Some of the documents that caught my attention include: