Sony Japan’s Brad Douglas has confirmed via twitter that the PS Vita will only support one PlayStation Network account per device. Users are able to login to a second account only after performing a full system restore, returning the device back to factory settings.
[The] only difference is that Vita requires you to do a factory reset when logging into a new acct, PSP does not
Reports surrounding this policy first appeared online over the weeked on popular gaming forum NeoGAF. The information originated from a Japanese hands-on event Sony held to promote the upcoming public release of the PS Vita, which is scheduled for December 17th.
Unlike the PS Vita, the PlayStation Portable does not require a factory reset in order to take advantage of a second PSN account.