I got plenty of good design and code considerations in this slideshow from Wordcamp Seattle 2011, by Michael Fields. I wish there’s a presentation video somewhere.
Titled Something Something Social Media: The Overdue Minority Report.
Writing Secure Plugins by Mark Jaquith. Creating Community with BuddyPress by Lisa-Sabin Wilson BuddyPress Groups API by Andy Peatling. How to in WPMU: Building a blog directory & Domain Mapping by Andrea Rennick. Will...
By Abhijeet Mukherjee from the recent WordCamp Delhi. Give it a look.