The PSN maintenance that occurred on Monday, 9th December, increased the number of portable devices that can be linked to a PSN. The previous limit was two, which means gamers can now link up to three PS Vita or PSP devices to their account, and download content to them. The maintenance period lasted for 7 hours, and followed the release of Firmware 3.01.
According to Sony:
“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.”
[Source: Sony]