Sony has thrown a dampener on plans to take advantage of the Vita's digital focus and lack of region locking, by limiting each console to just one PlayStation Network ID.
According to NeoGaf's translation of a Japanese FAQ reportedly given out at a press event, the console will need to be restored to factory settings before a new PSN ID can be used on it.
This is problematic in a few scenarios, most notably families or couples planning to share a single console, and those hoping to buy digital releases from international PlayStation Stores.
The PSP is also limited to one PSN ID per console; while users can save a second profile to another memory card and swap between them, content purchased on one cannot be accessed by the other, and the system must be formatted between swaps. The Vita may employ a similar system, making sharing between PSN IDs possible, if laborious.
The PlayStation 3, on the other hand, allows multiple user accounts and PSN IDs. Purchased content can be shared between accounts on the same machine, without region locking, making for easy digital "importing".