If you have a Verizon LTE iPad 3, you will see a popup message that says:
Carrier Settings Update
New settings are available. Would you like to update them now?
These settings will only update the PRL (Preferred Roaming List) which allows your Verizon equippment iPad to connect to new towers that Verizon has recently installed. This update is completely harmless and is recommended for all users. The update should only take a few seconds to perform.
After the update, the iPad3 shows a PRL version of 15102 (Goto General -> About -> Click on Carrier). Enter in the comments below the PRL that you have, if different. Didn't get a chance to write down the PRL before the update. The carrier settings are stored in your Micro SIM, so if you install a new SIM, you will have to apply the carrier settings again.
What are Carrier Settings Updates?
Carrier settings updates are small files (about 10 kb) that are installed on your iPhone or iPad Wi-Fi + 3G. Carrier settings include updates to Access Point Names (APNs), MMS settings, features such as tethering, and default apps such as Stocks, Maps, and Weather. You might receive notifications periodically about installing a carrier settings update.