See that image? If you try to play SimCity on the U.S. servers right now, you probably will. It's a little different from the image we saw last night, and the server issues we saw all throughout yesterday, but the problem remains the same: people who bought SimCity can't play it.
Right now it's 8pm GMT (Greenwich Mean Time, or 5 hours ahead of Eastern), and the servers that were supposed to reopen at 7pm GMT are still not open. It seems like you can play on some European servers at the moment, although that doesn't help anyone who has already started cities on regions with their friends on the U.S. servers.
SimCity's Twitter account also sent out a message that they're patching the servers right now:
So, yep. The game that went on sale yesterday still isn't working. Hopefully this mess of a launch is fixed up soon. We'll keep you updated in the meantime.