In response to post about issues with the difficulty of leveling a rogue, we also got information about the some of Cataclysm's overall leveling improvements from Ghostcralwer (World of Warcraft Lead Systems Designer).
This should be a little bit more informative and much more immediate than the mails that you occasionally receive from NPCs about new features. Hitting a new level while in the middle of questing and being able to at a quick glance find out what skills you'll be receiving if you head over to the class trainers will let you decide if you want to keep going or wait until later in the event of a skill you don't use that often.
While some will argue that this is yet another change for casuals, it's honestly a change for modern game design and keeping up with the curve. When your game is over 5 years old, there are often some basic things that need updating and the leveling process really is one of them.
World of Warcraft: Cataclysm will destroy Azeroth as we know it. Nothing will be the same. In WoW.com's Guide to Cataclysm you can find out everything you need to know about WoW's third expansion. From Goblins and Worgens to Mastery and Guild changes, it's all there for your cataclysmic enjoyment.