The notifications that pop up when your friends come online are very disruptive. Is there any way to turn off the notifications while remaining signed in? I didn't see any such option in the Friends or Settings apps.
Currently, there is no way to do this. You can turn off the notification light and sound in settings but cannot physically turn off the notification. This is, however, a feature that is being discussed on the PS Vita forums to be suggested for future software releases.
It doesn't work at the current moment. They just put a useless check box for it for them to not procrastinate on it. (Even though they probably will anyways.) I tried also turning off the light and sound for notifications, yet it STILL notifies with a light on the PS Button, however it never makes a sound in standby for a notification.