Sony Online Entertainment has been plagued by DNS problems since early Tuesday morning, causing players to intermittently be unable to access SOE websites, forums, and games. Today SOE issued an apology on their forums (if you can get to them) and social media:
We deeply regret the recent service interruption. We will be adding two days of membership time to all members’ accounts.
Because domain registration can take a while to filter through internet service providers everywhere, players may continue to have issues. In cases like this things are usually completely resolved within 48-72 hours. If you don't want to wait, you can also try to flush or map your DNS.