Mach 3.0 kernel. A replacement for Standard File. Significantly faster networking. Finder copies now FILL a 100MBit ethernet. Nearly everything is scriptable.
Folders can have scripts attached which execute when something is done with the folder.
Also of note, Apple has heard the criticism about their slow virtual machine, and is finally doing something about it. Todays JVM gets roughly 300 CaffeineMarks. Their target is currently 3900 or so caffeinemarks, but may well end up higher than that. QuickTime for Java. The example given was in looking at extending MS's security model to Apple's JDirect functionality.