Here you go...

Improved SMP support (multiple cpus in a single system)
CPU scheduler
Improved performance in memory constrained systems.
SMP algorithm optimization for operating system data structures
Ext3 performance improved (read/write I/O and directory scanning operation
Ext3 size upto 8 TB
Logical Volume Management (LVM)
Security Enhanced Linux (SELinux) and Mandatory Access Control (MAC)
Support for >2TB file size
XFS file system
I/O elevators
ACL
Network based crash dump