In addition to all the other changes mentioned, The Shattering (4.0.3) patch arrived on November 23, 2010, redoing all the zones in the old (classic) world.
Additionally, Blizzard has shifted the levels you need to ride mounts around. It's now:
- 16 for mount-like abilities (Druid Speed form, Shaman Ghost Wolf)
- 20 for normal mounts (4g skill, 1g mounts)
- 40 for very fast mounts (50g skill, 10g mounts)
- 60 for flying mounts (250g skill, 50g mounts) (Druids can train Flight Form for 3g)
- 60 for Flight Master's License (flying in the old world, post Shattering) (250g skill)
- 68 for Cold Weather Flying (flying in Northrend) (500g skill)
- 70 for very fast flying mounts (5000g skill, 100g mounts)
- 80 for extremely fast flying mounts (5000g skill)
Cataclysm also adds another two playable races: Goblins for Horde, Worgen for Alliance.
4.0.3a introduced new race/class combinations. At least one class was added for each race. The new combinations are: Troll Druid, Troll Warlock, Tauren Paladin, Tauren Priest, Blood Elf Warrior, Orc Mage, Forsaken Hunter, Human Hunter, Night Elf Mage, Dwarf Shaman, Dwarf Warlock, Dwarf Mage, and Gnome Priest.
Levels 10-60 also require 10% less experience per level than they did back during BC.
The rate you gain spells/abilities at has been changed. It is no longer every other level pre-60/every level post-60.
The rate you gain talent points at has changed. It is no longer every level post-10... instead it's spread out, maxing out at 41 talent points at level 85.