Summary:
1. Prominent features
1.1.
Blah
2. Driver and architecture-specific changes
All the driver and architecture-specific changes can be found in the [http://kernelnewbies.org/Linux_3.1_DriverArch Linux_3.1_DriverArch page]
3. VFS
4. Process scheduler
5. Memory management
6. Networking
7. File systems
8. Crypto
9. Virtualization
10. Security
11. Tracing/profiling