H1Z1 footage shows that, yep, it looks a lot like DayZ [Update: DayZ similarities addressed in Reddit post]
Update: SOE's John Smedley has addressed concerns and answered questions about the stream, in a post on the H1Z1 subreddit. In addition to confirming that H1Z1 will feature both first and third-person views, and a "deep in-game economy" that will be "entirely player driven", Smedley addressed the game's similarities to DayZ in a refreshingly upfront manner.
"How is this different from Day Z? - saw this a lot. Not going to give some politically correct dodgy b.s. answer. It is a survival in a Zombie Apocalypse game. So is Day Z. They have made a brilliant game (first I might add). They have a great vision for it and can count myself and most of the people on our team as fans and contributors.
"We're making the game we're making. Long term we plan on making this about a persistent world with a big landscape with thousands of players. The way we would like to see this roll out is much more like players building small enclaves or pockets of territory and hold out against a legitimate zombie threat that's ever present while others go it alone taking their chances.. These player built structures, forts and towns are one of the ways the players try to carve out some small space in a dangerous world."
"So this is our take on the Zombie Apocalypse with a lot of friends and hopefully some great enemies both living and dead. We're proud to be up front and say we love Day Z and the job they've done and we hope they enjoy what we make too."
The Long Dark's creative director reckons the apocalypse doesn't have to feature zombies - but, erm, here's one more open world post-apocalyptic game that does. As announced last week, Sony's entry into the DayZ genre is the wittily (if clinically) named H1Z1, a game that differentiates itself from Dean Hall and Bohemia's game by...well, that part's not totally clear yet, but it's been a fairly democratic process so far. H1Z1 game designer Jimmy Whisenhunt and technical director Tom Schenk took to Twitch a few hours ago to show off the game as it stands now; you'll find 50-odd minutes of walking, zombie-battering, scavenging and driving, in a game that admittedly looks very pretty but so far doesn't seem to boast any distinguishing characteristics.
Whisenhunt took to the active H1Z1 subreddit after the stream to answer a few questions about combat. You'll be pleased (or not) to hear that combat will be slightly slower in the finished game, with one-shot-kill headshots across the board (zombies were a bit too resistant to bullets in the stream), and with rare military-spec weapons available to players who do a bit of digging, or who look in the right place - ie not in an average suburban house.)