Is there a way to turn off mobile (3g) data on the Vita?
I plan on picking up that model but not using the 3g, at least initially.
If having 3g disabled is going to be a battery drain, I might have to reconsider.
There hasn't been much discussion that I have seen about this, but from what I can tell, the main reason why the battery life is so awesome in standby mode vs. the 3DS is because the system seems to wake the network connection periodically and only when needed.
For example, the way near works is that it wakes up the PSP every hour or so, scans the nearby wifi networks (or uses the GPS to geolocate) and goes back to sleep. Near only needs a network connection when you upload the location data to their servers, which happens every 8 hours or so if you allow it to do it automatically. Compare to Streetpass which requires you to have the wifi on continuously when you are out and about.
Similarly PSN messages aren't pushed to the device, you can set a polling frequency for those (never, 15 mins, 30 mins, hourly), and the default is never (so you only get text messages when you manually refresh the messaging app). When it's not checking messages the wifi is completely turned off, so it's not continually draining the battery (I would imagine that the 3G model works similarly)
I would think that you would go through a limited 3g data cap pretty slowly the way it is set up. There are some annoyances though, like when I sleep the machine sometimes it will suspend my background downloads, which is annoying. But overall it seems to work pretty well and you definitely can't complain about the standby battery life...