Sony have announced plans for a new scheduled maintenance for the Playstation Network today.
The latest update to the PSN will take place on August 17 at 9:30PM PDT and will last 90-120 minutes. You will not be able to use Playstation Video, Account Management, or buy anything on the Playstation Store. Nothing else will be effected during this time.
The exact reason for the scheduled maintenance has not been stated by Sony.