T-Mobile USA has switched on its unlimited 4G data plans, using the new tariffs to celebrate its tenth anniversary. Announced in August, the new "Unlimited Nationwide 4G Data" plan is now available in stores, with no overage charges, no throttling, and no limit on how much you download on your device, priced from $20 on top of your regular voice plan.
If you've got a Value voice and text plan, the unlimited 4G data will cost $20 monthly. Those adding it to a Classic voice and text plan will pay $30 per month for the unlimited 4G data.
Meanwhile, T-Mobile USA is also offering a sale on "select 4G smartphones" to mark the launch. The HTC One S, for instance, is free (after a $50 mail-in rebate) with a new, two year agreement. The option wasn't available through T-Mobile's webstore at time of writing, but should be popping up sometime today; alternatively, you can head to your nearest brick & mortar store to grab the same deal.
It's worth remembering that, for the moment at least, T-Mobile USA's interpretation of "4G" is HSPA+ - the carrier lacks an LTE network, unlike AT&T or Verizon. Still, speeds of up to 42Mbps downloads are possible, theoretically at least.