It's said that nothing is certain but death and taxes, but whomever first uttered those words clearly didn't own a PlayStation. For if that person did, surely he/she would have added 'PlayStation Network downtime' to the list of life's absolute certainties. As it were, that's precisely the case today, as Sony spends the entire day performing routine maintenance.
"Regular maintenance is a necessary part of operating a service such as PSN. As part of our efforts to continue to deliver you a world-class online entertainment experience on your PS3 and PS Vita devices, we will be performing maintenance on the network on Thursday, May 24th, starting at approximately 8:00 am PDT / 10:00 am EDT and concluding around 11:00pm PDT / 2:00am EDT," Sony announced in a blog post.
That means you won't be able to access the PlayStation Store or PlayStation Home, though online play will not be affected. You'll also still be able to use apps like Netflix and Amazon Instant Video (provided you signed into the network within the past 5 days) while Sony's web monkeys go bananas maintaining whatever needs to be maintained.