It's been amazing to see how Sony has systematically stripped away every advantage the PS Vita had over rival systems, and today's bit of news seems to cap it off perfectly. The PS Vita will only let you use one PSN account per system, undermining its ability to region switch and ensuring your family can't share it.
If you want a new account, you'll need to reset the Vita to its factory settings. You won't be able to simply log in with a new user, like you can with the PSP. [Edit: Dale actually says you couldn't do it on the PSP either. However, you only had to delete the account, you didn't have to reset the entire system to factory defaults.]
One of the Vita's big selling points was the fact that it wouldn't be region-locked, but you won't be able to digitally download games from another region's store if you're tied to a single PSN identity. I'm sure Sony will inevitably claim this is another anti-piracy measure, but a significant number of users are pretty disappointed.
I'm still excited to see what the Vita can do, but it's a shame that Sony's still stuck to its prehistoric thinking with all the hot technology at its disposal. Marrying restrictive, outdated business models to brand new tech always strikes me as rather tragic. What a waste.