4e - The Three Tiers

Characters are broken up into 3 tiers of power based on their level in 4th Edition. Levels 1 - 10 are the Heroic Tier (save the town from the ogres), Levels 11 - 20 are Paragon (save the kingdom from the dragon) and Levels 21 - 30 are Epic (save the world from the insane demon lord).

As part of the ramp up to 4e's release in June, WotC will be releasing exerpts from the 4e books. Here is the article on the three tiers of power and includes a chart showing how many powers a character gets at any given level.