It's probably been covered before, but the search feature failed me.
Doing some low level quests in Tirisfal and Silverpine (Forsaken starting zones), I've come across several quests that mention the fall of the Lich King and the Wrathgate incident. The starting cinematic for the Blood Elves also mention the death of Kael'thas. Which is all fine and dandy since I've already been through Outland and Northrend on my Druid and can relate to it all.
What I'm curious about is when my low level toon hits level 60 and moves to Outland and 70 and moves to Northrend. Will I then participate in events that have already happened? Seems like they sort of broke Outland and Northrend off of the timeline, but I can't imagine why. Makes those two areas worthless, unless they revamped the zones to also indicate that the Lich King and Illidan are dead.
And I know I predicted this when I first heard of the changes to Azeroth in Cataclysm. I knew it was going to mess up the chronology of the game something fierce. I guess I'm just gloating over a cup of 'told you so'.