More specifically, it's Roland Kickinger, a really big dude who actually played a young Schwarzenegger in the 2005 TV movie biopic See Arnold Run. He's guest-starred on a slew of sitcoms, and had a part in Lethal Weapon 4. He will also play the Hulk in the anxiously awaited (by which I mean dreaded) parody Disaster Movie this Labor Day.
Kickinger will take over Schwarzenegger's T-800 character, an early model cyborg that was sent back in time in all three Terminator films -- first as the villain and then as a hero after being reprogrammed by the resistance. In the latter two films, he bonded with his human charges and sort of became the heart of the franchise, as well as its comic relief. It was definitely Schwarzenegger's greatest achievement as an actor, such as it was. I doubt they'll be trying to recreate that in Salvation, not least because the characters encounter the robot 20 years before the events of the earlier films. (Damn time travel.)
Some slightly spoilerish quotes from the Clinton News-Record article announcing Kickinger's involvement, after the jump.
"There's a very strong scene in the film where John Connor for the first time meets the Terminator, and he doesn't know if he's a good guy or a bad guy," said Kickinger.
"It's Arnold's character in the first Terminator. That's basically my role, but 20 years before, so it establishes how the Terminator [came] about."
[hat tip: Ain't It Cool News]