Incase you missed it, Sony's 1.65 Firmware Update for the PlayStation Vita was pulled due to a "technical fault". Today, Sony has released a new 1.66 Firmware Update as a replacement.
1.66 will include all of the features in 1.65 and more. Some of the changes you can expect with this update include a "Notification Alert" option which allows you to turn the alerts on and off, a Caps Lock in the On Screen Keyboard, and a percentage bar while a game installs. Also, Unit 13, and Near have improved functionality.
This PS Vita update is 97MB and is available now. Click here for more details on this update. Happy Installing! Hopefully this one doesn't have any technical faults.
Source: PlayStation Forums