Hope you didn't have anything planned
Remember that DDoS attack on the PSN networks last weekend? Well there was supposed to be a scheduled maintenance day that following Monday, but it was postponed due to the unexpected issues that took place. That day has come sooner than expected -- the PSN will be limited from 9:40AM to 4:50 PM PST today.
As a reminder, if you've signed into the network from August 23rd on, you can play games and access apps like Netflix. However, the PlayStation Store, Home, and Account Management options will be completely down.
Maintenance updated [PlayStation Forums]