As we already know, the OnHub will be using a variety of radios, including Wi-Fi (2.4 GHz and 5 GHz), Zigbee/Thread (802.15.4) and Bluetooth/BLE.
Now, there's lots to pick through in these docs, but if you want to get really specific about the flavors of Wi-Fi, we know now they will be using 3x3 MIMO, which is pretty standard in most consumer routers. Since Google had managed to pack in so many radios and is pretty forward leaning on this router, I thought they might be using 4x4 MIMO, which some cutting edge routers do use today.
But that's a negative, according to the FCC docs.
There's probably lots more here for you RF engineers, so have at em and let me know if you find anything interesting in the comments.