I think they arw just testing the equipment. Its not official yet .and I have not been able to connect outside of my home area.
Ever since I moved here in 2008, it always seemed like Verizon country here... so AT&T was always slow to update... first with just 3G, then HSPA+, and now LTE. But I am glad that they finally flipped the switch for LTE!
Honestly, for AT&T to have Denver lit up this late in the game is a joke. Birmingham, AL has LTE before Denver does. BIRMINGHAM!