I looked at the play offline button, but its currently inactive as well. I'm not sure of any other way to login.
My account seems fine, as I logged in with no problems to the forum. Additionally, I loaded the game some time within the past two weeks, so I had most of the updates and it worked fine then. However, I know some updates were loaded tonight, and the most recent version listed on the patch notes from the downloader is 1.5.3.
I'm on a Windows 7 operating system, and did recently update windows (through windows update). I don't think I can roll those updates back to test without them however. If there is a way to reinstall the game, I could try that option to make sure all the files are still in tact.
That's all the information I can give. If anyone else has had similar problems, let me know if they have been resolved.