A number of users on WebmasterWorld have been reporting that their Google AdWords accounts were inadvertently canceled. According to Google, this was a mistake:
Thank you for your email. I'm sorry to hear that you've had trouble with your AdWords account. We've identified a known technical issue affecting a limited number of accounts. Our engineers are currently working to solve the problem and hope to reach a resolution shortly. Also know that I have reactivated your account.
Google claims this has only affected a "limited number of accounts." They have not released percentages or numbers as to the true number of accounts that have been canceled due to this technical glitch.
[Hat Tip: PoorSEM.com]
Forum discussion at WebmasterWorld.