Information made available on their site https://binance.zendesk.com/hc/en-us/articles/115000773732--Free-Trade-Fee says "All the trading fee in our Binance.com will be free from July, 25th,2017, 0:00 to August 24th, 2017, 24:00 (Beijing time)."  

I expect some major upward price movement when and after fees start being paid using BNB, with new listing there would be some serious market action on Binance also combined with upcoming ICOs.