In another exclusive -- this time from Eurogamer -- Bioware unveiled information regarding "Advanced Classes". It seems each of the 8 major classes will be split into 16 advanced career choices. According to Eurogamer, "Each Advanced Class will have its own skills and abilities that define its role on the battlefield, and in some cases grant access to new weapon and armour types." For instance, the Sith Warrior class is broken into either the Juggernaut or Marauder careers. This will not affect the story of your character, but it will determine the role your character plays in group combat.
[Update: Advance Classes information is now on the official site]