[UPDATE] At 1:40pm PT, the PSN Status Page stated that everything was back up and running.
After reports began coming in on Twitter, NeoGAF and Reddit regarding problems with accessing the PlayStation Network, Sony updated their PSN Status Page to state that everything is currently experiencing issues:
Gaming & Social (PS4, PS3, PS Vita, Web)
You may have some difficulty launching games, applications, or online features. Our engineers are working to resolve the issue as soon as possible, and we thank you for your patience.
PlayStation Store (PS4, PS3, PS Vita, Web)
You may have some difficulty accessing features and products on the PlayStation Store. Our engineers are working to resolve the issue as soon as possible, and we thank you for your patience.
Reports first began coming in regarding the problem around 12pm PT today. We’ll keep you updated when we learn more.