Required Peripherals
Famitsu says that a Memory Card is pretty much a requirement, as some games will require the card. Games that require a card can't even be booted up if you don't have one.
External Video Out
The system does not have external video out.
PS3 Connectivity
Memory Card data management and Trophy sharing. You can also view video and music via Remote Play. PS3's Torne DVR device can also be used once you've updated its firmware.
PSP Software Compatibility
You can up the visual quality through bilinear filtering. This can be toggled on and off.
Use of PSP and PS3 Peripherals
The system cannot use PSP and PS3 peripherals
Internal Software
At shipment time, you can use the following built in apps or functions: Welcome Park (introduces you to the controls), Party (a chatting app that can be used in games), Photo & Camera, Music, Video, Near (a social app for interacting with other Vita systems in your area), Browser, Group Messaging, Friend, Trophy, PS Store, Remote Play, Content Management and Settings.
Parental Controls
For 3G, content will be filtered by default. If you want this feature turned off, you have to fill out some paperwork at the NTT DoCoMo shop.
GPS Without a 3G Contract
You can still use GPS, but 3G can acquire positional information faster.
Current 3G Usage
You can check your current 3G usage through an app called "Network Operator."
Wi-Fi VS 3G
The system will first attempt to connect via Wi-Fi. If no Wi-Fi connection is found it will connect through 3G. While connected through 3G, even if the system finds a Wi-Fi hotspot, it will not automatically switch.