PSVita supports multiple PSN Accounts per system, but only if you have multiple memory cards.

[Euphoria14]

Acevil said:

theprof00 said:
Why do you need multiple accounts? I just don't get it.

To share with family members or roommates. 

True, but even then I wouldn't consider it any kind of deal breaker when no other dedicated handheld gaming device gives the option either.