@Azteck: That is completely incorrect. With ~120 active skills and ~15 passive buffs to choose from per class, even a cursory glance makes the following possible roles obvious:
Barbarian: Active DPS / CC / Tank
Demon Hunter: Active DPS / Passive DPS / CC
Monk: Active DPS / CC / Tank / Healer
Witchdoctor: Active DPS / Passive DPS / CC
Wizard: Active DPS / Passive DPS / CC / Tank
Of course the level of freedom that exists between skill selection and itemization means that players will be able to go all in on a role or create their own unique hybrid build. I look at the D3 skill calculator and almost feel crippled by the impossibly large number of options available to me.