I think the design idea is for Gladiators/Paladins to hold the bosses while Marauders/Warriors hold crowds of adds and trash mobs. At low level play it kind of doesn't matter: friends of mine have succesfully run pre-30 instances with no tank at all.
With that said, I know nothing about the jobs, but I assume they'll follow the same general principles as their base classes.
With that said, I know nothing about the jobs, but I assume they'll follow the same general principles as their base classes.