This is the new Richard Franiec GM1 grip (more info at http://www.kleptography.com/rf/)
Dpreview published their full GM1 review. The camera earned the Gold Award:
The GM1 offers much of the features and image quality of its Lumix GX7 sibling in a much smaller, lighter package. A few concessions have been made to reduce the size so drastically, namely a lower-capacity battery, but it’s an excellent option for casual shooting.