Meike announced a new battery grip you can preorder now at Amazon US and Amazon UK,

The grip allows for easier vertical shooting, double the battery capacity, and features a wireless remote with a 100m range and an LCD display.

Features:
Working Voltage: 7.2V-8.4 (grip) /3V (remote)
Working Temperature: 0 ~ 40°C
Applicable Battery (Not Included): 1-2pcs NP-FZ100 (for grip) / 2 x AAA batteries (remote)
Size: About 122*66*61 mm (grip) / 108*30*21mm (remote controller)
Weight (batteries not included): approx. 230g (grip) /32g (remote)