EDIT: deleted some needless confrontational stuff
Ontopic...The sheet shown at the keynote say Intelligence is the prime ability for the Warlock (bound to disappoint some) and Charisma for Socerer (expected).
Warlocks get +1 to Int or Dex or Con. 6+Con HP. Proficient with light armour, basic and finesse weapons and some other stuff that's blurred out. No idea how their magic works but mike talks about "bargains", which might be just fluff.
Sorcerers get +1 to Cha or Con. Your HP and proficiencies are non-existant, but defined by your sorcerous origin (basically Bloodline from PF I guess).
Then comes the interesting thing. Sorcerers get:
-Willpower (3 at lvl 1, 4 at lvl 2)
-Spells known (2 at lvl 1, 3 and 4 at the next two levels)
-and then it's a bit blurred out but I'm confident it says Max Spell Level and it seems to be 1 for the first three levels
So I think it's a safe bet Sorcerers pick spells known (probably from the same list as the wizard), which can't exceed the Max Spell Level and then spend Willpower to cast those spells (whether it's 1 Willpower per spell or 1 Willpower per spell level remains to be seen).
Finally, if I let myself speculate a bit, maybe they will let you do other stuff with Willpower, like maybe raise the DC of a spell or convert it into damage dice for a sorcerous blast or something.