Here are the architectural overview pages for Project Higgins and Project Bandit:
Higgins
Overview: http://spwiki.editme.com/HigginsIntroduction
Presentation: http://spwiki.editme.com/HigginsOverview2
Bandit
Architecture: http://www.bandit-project.org/index.php/Architecture_and_Design
Roadmap: http://www.bandit-project.org/index.php/Roadmap