A new playtest report on the official site provides a number of clues regarding 4th Edition combat, including concepts such as a "second wind", a "wizard strike" and an "immediate counterattack".
* First we have Heron and Tian being the only characters to spot the goblins, and thus the only ones to act in the surprise round.
* We then have Heron, who uses an "immediate counterattack" upon being missed by a goblin bowman, and who takes two shots back on his turn (he's a 1st level character).
Their second impression came squarely from the three arrows with which Heron skewered the hapless goblin sharpshooter in the loft. That poor goblin fired on Heron, missing but triggering an immediate counterattack from the ranger, who followed up with two more arrows on his turn. The sharpshooter was dead before the third arrow struck home.
* Domna, a warlord, uses some kind of bard-like ability to boost her allies in addition to attacking a wolf. It sounds like the "Leading the Attack" White Raven combat maneuver from Book of Nine Swords.
* Sasha uses something called a "wizard strike" with her staff, which both injures and pushes a wolf.
* Heron, the archer, moves away and regains some hit points on a "second wind" (Star Wars Saga Edition has a second wind rule: when your character is below half his total HP, he can regain points equal to 1/4 of his total or equal to his Con score, which is higher; usable once per day, takes a Swift Action; some feats, etc., allow more than once use per day, but never more than once per encounter; PC classes can do it, but NPC classes cannot.)
* Tian misses a goblin, who is then able to move away without provoking an attack-of-opportunity.
But then the first regular round started. Domna rushed a wolf and missed it, after shouting encouragement to her friends (providing a small bonus to them). The wolves continued to tear at Heron, almost sending the unfortunate ranger to death’s door. Sasha used a wizard strike with her staff, not only injuring a wolf, but also pushing it away from the prone Heron. This gave Heron the room he needed to stand, move away from his assailants, and regain a few hit points with a second wind. On his first regular turn, Tian used his second wind, then pursued the goblin by leaving the front door and running to intercept at the tree. He missed the wily skirmisher with his attack. The goblin cackled and backed away, then hurled another javelin at Tian—for another natural 20! Down Tian went, dying. Moving closer to Tian, the skirmisher started to reach for the knife on his belt to finish the rogue off. Robozcniek cut that thought short, literally, running across the battlefield, then charging the skirmisher and finishing the little dastard with one swift longsword stroke.
* An "initiative count" is mentioned "coming to the top again", which suggests there isn't a drastic change in that rule from 3rd Edition.
* Sasha uses another "wizard strike", which blasts two wolves, pushing one away again.
* Domna, the warlord, "uses her tactical acumen to attack in such a way that the wolf she hit opened itself up to Robozcniek".
On the second regular round, Domna struck the wounded wolf, trying to keep it off Heron. That wolf attacked Domna, but she fended it off with her shield. But the uninjured wolf smelled blood, and it took Heron down again, this time knocking the eladrin out. Sasha maneuvered to blast both wolves with another strike from her staff, pushing the one attacking Heron away again. Robozcniek rushed across the battlefield a second time, and he terribly wounded the wolf that had been attacking Heron.
As the initiative count came to the top again, Domna used her tactical acumen to attack in such a way that the wolf she hit opened itself up to Robozcniek. The warforged struck true, and the wolf collapsed in a heap. Badly wounded and alone against many enemies, the remaining wolf tucked tail and ran, but Sasha was having none of it. She pulled out all the stops and set off a fiery blast around the fleeing beast. It tumbled down, still smoldering.
In addition, we can note:
* Flanking and tripping both appear to still be in.
* No mention of confirming a critical hit (although the author may have just not mentioned it).
* Seems the Tiefling has company in the new races, with Eladrin and Warforged. At the very least, it being mentioned as a converted 3.5 game, no mention of conversion issues is raised.