Sprint really wants you to apply the latest OTA update to version 2.08.651.2 on the HTC EVO 3D. In case you haven’t already manually polled the servers for the update (Settings > System Updates > HTC software update), or if you ignored HTC’s network-initiated update prompt that started rolling out yesterday, Sprint will remind you about the update again through a message in the Sprint Zone app.
Depending on your notification preferences in the Sprint Zone app, you may have already received a notice in your notification bar that an update is available for your phone. Pressing the notification will take you to the web page you see at the right, touting all the benefits of the update.
Of course, if you’ve already rooted your phone and removed the Sprint Zone app, you’re in the clear and won’t get this reminder.
I have never known Sprint to send out OTA update notices using this method before, so they must really want you to apply this update. In any case, they must not be too concerned that this update will finally allow users to unlock the bootloaders on their phones using an officially sanctioned method.