Although that PSN downtime probably fails into a different category as it was a response to being hacked. Sony intentionally took the service down and kept it down to investigate and fix their security holes. Basically the equivalent of temporarily closing a brick and mortar store after a robbery compared to being involuntarily closed because no one could find the right set of keys to unlock the store's front door.

looks familiar to me also. was roblox also hacked?

From the blog post it sounds like no. They say a service got overloaded due to an increase in the number of datacenters and triggered a bug.