According to Sony, the earthquake has caused difficulty in connecting to the PSN, and it urges players to backup their data. Sony has apologized for any trouble caused by this, also sending it deepest regards to those affected by the quake.
What's more, Sony's PlayStation information call center and repair center were both suspended by the earthquake. Sony doesn't have an ETA for when service will continue.
Microsoft was also affected. The company's repair center, which is located in Fukushima Prefecture, is now shutdown. Like Sony, Microsoft doesn't say when the center will reopen. What's more, the company decided to postpone a "Gold Member Starter Kit" it planned to offer on March 17, due to the effects of the earthquake.
Xbox Live appears to have held up better during the quake than the PSN. For example, the PS3 downloadable content for Assassin's Creed: Brotherhood was delayed due to the earthquake. The Xbox 360 version is slated to be available today, March 15, in Japan.