The human & halfling both have a +1 to all defenses from an unknown source.
Looks like daggers & short swords get an extra +1 to hit over other weapons. Ranged attacks get Dex bonus to damage, even with normal bows. The ranger is rather scary, dealing 1d10 (bow) +4 (Dex) +1d8 (ranger ability) per attack at first level. The fighter has +1 hit & +2 damage from some source (class bonus? dwarven weapon training?). It's curious that the halfling is using a short sword rather than a more damaging weapon... some restriction based on Small Size?
Normal move is still 30 ft. The halfing, dwarf, and cleric move 25 ft., and all wear (in 3e terms) medium/heavy armor, so it appears everyone has a base move of 30 ft. and heavier armors slow you by 5. The ranger wears hide armor and is not slowed, so presumably it's no longer medium armor. Looking at it some more, hide armor and leather both provide the same AC bonus (+2), so I guess hide is just a variant of leather. Scale armor & plate mail also provide the same AC bonus (+6). Chainmail is +4 AC. As many have already noticed, large shields appear to provide a +2 bonus to your Ref defense (and thus to AC as well).
Warlock powers use Cha for hit & damage. Wizard powers use Int. The Warlock has a Wizard power (ray of frost) that uses Int instead of Cha, further backing this up. Cleric powers obviously use Wis. With the paladin, you can't tell since that character has a 16 in both Wis & Cha.
Warlock starting Defenses: +1 Ref, +1 Will
Paladin: +2 Will? (taking into account the mysterious +1 to all defenses on the halfling)
Cleric: +2 Will (ditto with the human's defenses... or maybe it's a divine thing)
Fighter: +2 Fort
Ranger: +1 Fort, +1 Ref, +1 Will (I'm wondering if one of those is an eladrin racial, or if rangers just get more defense than other classes)
Wizard: +2 Will