Sprint has started working on the infrastructure upgrades required to support their LTE rollout in the greater Jacksonville area. You might see engineers from Ericsson working in and around Sprint tower facilities as they perform the swap outs of the old equipment with the new.
Sprint by policy won't announce the availability until at least 50% of the coverage area has active service, which is currently planned in Jax for November 2012. Those Sprint customers with the new Samsung Galaxy S3 may notice their "4G" indicator appear from time to time as engineering tests proceed. The rollout of these upgrades on the First Coast will continue until March 2013.
We are currently ahead of Tampa in the 2nd wave of LTE rollouts nationally and the first in Florida to get them.
For those people with 3G Sprint handsets, you will see improved performance as Sprint not only retires obsolete backhaul (the data pipes supporting the towers), but also migrates the 3G infrastructure to remote radios.
Also as part of this, Sprint will be reducing the size of their "refrigerator cabinets" that store their equipment to a size no larger than a desktop computer.
Sprint maintains an LTE upgrade blog for the Jacksonville/First Coast market.
http://s4gru.com/index.php?/blog/1/entry-278-jacksonville-network-visionlte-deployment-schedule-update/ (http://s4gru.com/index.php?/blog/1/entry-278-jacksonville-network-visionlte-deployment-schedule-update/)