It's time to update your Vitas! You gain access to some (SOME) PSONE classics as well as some new browsing options and optional touch controls.
Here's a video detailing the update:
For now, there are only a few PSOne games listed as being available, though I've read that there is a fairly simple workaround to get more games on the Vita, as long as you have a PS3: download the items to your PS3 and transfer the uninstalled data from there to the Vita. These games aren't on Sony's approved list, so be aware there may be some issues within the games themselves (they're not tested and approved).
I also read that the new update locks the memory card to one account -- make sure you back up data before you update (always do this before an update!)!