No source, just rumours published in a lot of sites. It is already surprising that Panasonic offers a body with sensor stabilization, since their path was always OIS.
And since they already have a video-focused flagship (the GH3), I guess that the emphasis in this one will be fotography. It will probably have 1080p in 60, 30 and 24 fps, but I guess that in bitrates very close to the G6. And attractive package, but that will not surpass GH3 in video. As I said, all personal guesses.