Sony has announced that the maintenance taking place today will bring with it an increase to the amount of portable devices that can be linked to an account. The current limit is two but after today that will increase to three, and will affect PSPs and PS Vitas. So, if you want, you can have three Vitas (or PSPs) sharing one account.
“This maintenance will increase the number of devices that can be activated by an account as a portable gaming device. This means that you can now activate up to three portable gaming devices (PSP (PlayStation Portable) and PlayStation Vita) on your SEN account. This new portable gaming device allotment is in addition to the other network improvements being implemented during this downtime.”
During the maintenance online gaming will be available if you are signed in prior to it beginning, but access to the Store and Home will be unavailable.