1. Facebook Science & Social Graph (Video)
2. Scale at Facebook
3. Facebook Chat Architecture
4. Facebook Blog
5. Facebook Cassandra Architecture and Design
6. Facebook Engineering Notes
7. Quora – Facebook Architecture
8. Facebook for 600M users
9. Hadoop & its usage at Facebook
10. Erlang at Facebook: Chat Architecture
11. Facebook Performance Caching
12. Facebook Connect Architecture

refer:http://stackoverflow.com/questions/3533948/facebook-architecture