It appears that any hope you may have had of letting your best gaming pal have an account on your PS Vita is gone. Also gone is any hope you have of getting and playing games and other items not usually available in your region.According to a post from NeoGaf member, mehdi_san:
"I just got back from the Vita event in Osaka... There also a FAQ section at the end, and that's where I found this bad news:
"Quote:
"Q: How many PSN account can be set up on a Vita system?
"A: Only 1 account. If you want to to use a different account, you need to format the system to factory settings."
So, yup, region-locked and single user PlayStation Vita ahoy.
More detail here