Let's see. First off, here's me guess as to what these builds do and don't do:
-DO influence which "secondary" stats your character makes use of. (Artful dodger as Charisma rogue vs. Brutal Scoundrel as Strength rogue, but both are secondary to Dex.)
-DO affect the way various powers work.
-DON'T limit WHICH powers you can take... although some are way better with a particular build.
So here are my "educated" guesses:
-Fighters: 1h-weapon-and-shield or 2h-weapon. Sword-and-board fighters have more defensive capability, while zwiehander fighters pump out more damage. If Strength is the fighter primary stat, then I'd think 1hander guys would have Con as their secondary stat and 2hander guys would use maybe Dex.
-Clerics: Melee-focused, offensive-spell-focused, and healing-focused. Melee clerics are more resilient in melee and enjoy smacking down enemies by hand, while spell clerics use lots of power words and so on. Healing-focused clerics have more leader-y abilities, for players who really dig the "support" role. Since Wisdom is the primary stat, I'm guessing Con (or maybe Str) as a secondary for melee clerics, Int for spell clerics, and Cha for healing clerics.
-Wizards: Hm. One build for each implement, I guess? I'm actually hoping that they push secondary stats for wizards this time around. Maybe Wis for orb-users, Cha for wand-users, and Con for staff-users?
-Rangers: Easy one, archer vs. dervish. The archer gets all those ranged powers, while the dervish gets two-weapon fighting and related swashbuckly goodness. (I'm guessing that an optimal swashbuckler in 4e will be a ranger dipping or multiclassing into rogue.) Dex is obviously the main stat, so maybe... hrm. Wisdom as a secondary for archers and Cha (or Str) for dervishes?
-Warlocks: Another easy one, the three pacts. Here I'm not sure how (or if) secondary stats would be parsed out. Assuming Cha as the primary stat, Int as secondary for demon-pact, Wis for fey-pact, and, um, Insanity for star pact?
-Paladins: Judging from the Smites article, Charisma is their primary stat, with Wisdom as a strong secondary. I really don't know how the builds would break down, though.
-Warlords: This one's almost pure guesswork. Assuming Cha as the primary stat, Tactician (int) vs. Inspirer (wis)? The former could be heavier on offensive, cooperative powers (Feather Me Yon Oaf) and the latter more focused on healing and buffing.