The Druid class has been revamped. It’s much closer to the PHB class now. Flavorwise, the ties to a specific guarded land have been removed from the class – unlike previous versions of Dark Sun, the Druid class is now untethered. A Prestige Class representing the scary-powerful-druid-as-a-gardener is being polished.
Also seeing an update is the Ranger class, featureing some simplifications and clarifications.
Rounding it out, the Rogue class has also been updated – normalized against the PHB with a few new 10th level options thrown in.