Just now I got 4g signal in Gaithersburg, MD where I work. I didn't see any noticed that it was officially switched on. I'm reading these signals in a building so take them with a grain of salt. I also ran a couple of speed tests which were hit or miss.
Signal info:
Strength: -90dBm 4 asu
Network Type: LTE:14
PRL: 25010
Speed Tests:
1) 8.98 Mbps down, 0.25Mbps Up, 72ms ping
2) 4.05 Mbps down, 0.21 Mbps up, 75ms ping
3)7.14 Mbps down, 3.94 Mbps up, 89ms ping