Oh what a difference a year makes. In September of 2010, MetroPCS (NASDAQ:PCS) was the first to launch LTE service in the U.S.  And now just one year later, three operators have deployed LTE service in some form and the number of LTE devices available to end users has grown dramatically. Indeed, LTE device momentum is accelerating. Although it is difficult to quantify how many LTE device models have been sold so far, operators certainly are working hard to get consumers to migrate to LTE devices and LTE networks. There are a handful of devices in the market and even more in the pipeline. Although the first LTE devices for Verizon (NYSE:VZ) and AT&T Mobility (NYSE:T) were USB modems, smartphones and tablets provide carriers with a greater chance to differentiate their LTE networks. Here is a rundown of some of the most high-profile LTE smartphones and tablets currently available from U.S. carriers. Slideshow