The website Discover Mirrorless has posted a video interview of various US Panasonic reps talking about the GH3. This is a peculiar video because these reps actually say things. Companies usually keep their executives and PR people on very short leashes. It's why talking to them is usually totally useless.
This video, while much longer than it needs to be, and the host is just awful, has some useful information. For me, the biggest revelation is that the GH3 does in fact have a multi-aspect sensor. For some reason, it is just disabled in firmware. I don't know if they plan on enabling it in the future. I suspect that they do, because, why not? For many a filmmaker, this is a big deal. The GH2's 1.8x sensor resulted in some pretty serious vignetting when using anamorphic adapters and considering how popular iscorama adapters became for the the GH2, it makes a little sense. It's still very strange, though. Why not just provide the ability in the menu system? This is aimed at pro-thusiasts, and trust me, they understand how to change settings.
Adding to the strangeness is a clean, uncompressed HDMI output, but they won't be advertising that. Wha? Why not? That's a pretty big deal. Instead, they focus on the myriad wireless ways that the camera can connect, which are best for photographic work... even though they admit that wasn't the focus.
Their focus on video over photography is apparent even in what they explicitly say. They mention a focus on video with their new lenses, which leads me to believe that the video performance of them is going to be very good. They're still over-priced! They also talk about how making the argument to move over to the GH3 from existing systems is more difficult when looking purely at photographic applications. This camera was expressly built from the ground-up as a hybrid camera.
One point of severe concern in the video is the stuttering response to the question about low-light ISO performance. I guess we'll see when we see.