Today, Ultimate Marvel vs. Capcom 3 received the first title update we've seen for a Vita game -- an update containing the free "Heroes & Heralds" mode. When I tried to load up the game to test online again, I was alerted to this fact, and then kicked out to the main menu.
Having since completed the procedure and updated the game, I thought I would demonstrate how updates are applied on Vita games. Welcome to the future!
Here's what I was greeted with upon trying to sign in within the game, telling me to back out to the LiveArea (a screen the Vita displays when you click on an app's icon, with links to DLC, the manual, etc.) The Vita's built-in screenshot function was disabled while this message was up, hence the hasty phone snapshot.
Here's UMVC3's "LiveArea." The arrow (added by me) is pointing to the button to apply an update. That's a pretty good icon, right? I guessed that was the one for "update," and I was right.
Tap the "update" button and you'll get an explanation of the update, and the option to download it.
You can then follow its progress, like any other download, in the menu at the top right corner of the screen.
Having to back completely out of a game to find and apply the update is kludgey, but once you've figured that out, it's reasonably easy to use. And now that you know how to do it in advance, it'll be even easier.