Owners of the LTE enabled HTC ThunderBolt will see "Enhanced data connectivity when accessing the Verizon 3G network" which is interesting since it was the carrier's 4G network that went out the other day. Some owners of the device must have had a hard time finding the SMS or MMS that they just sent because the upgrade will make sure that messages are stored in the right application (Inbox, Sent, etc.). Also, it is important that when checking the weather on your ThunderBolt, it shows the conditions outside for the proper city. The upcoming update will make sure that the weather widget displays the correct location.
There are more things that the upgrade will improve. Check out the sourcelink for the list. A precise date for the upgrade has not been announced yet, but it could come to your unit at anytime.
source: Verizon via AndroidandMe