I found myself needing space on my Vita for the first time when trying to download Final Fantasy X/X-2 HD. Then I learned there is no easy way to delete things from your Vita aside from deleting individual bubbles, which deletes games and saves. Similarly, I'd have to go deep within system settings to see if I'd made enough room because I can't remember three numbers at once. It's why I know my birthday, but not the year.
Anyway, there a Vita firmware update that is too late for me, but maybe it will save you some hassle, because it brings a memory card content manager.
It also lets you display 500 applications on the home screen, up from 100. Which was apparently a problem for some of you? Are you nuts?
There's also voice messaging, so expect me screaming No Doubt lyrics into your ears if you're one of my PlayStation Palz™. SORRY I'M NOT HOME RIGHT NOW I'M WALKING INTO SPIDERWEBS, LEAVE A MESSAGE AND I'LL CALL YOU BACK.