I received this email today:
Your AdWords Google Account is stoped.
Dear Google AdWords Customer,
We were unable to process your payment.
Your ads will be suspended soon unless we can process your payment.
To prevent your ads from being suspended, please update your payment information.
Please sign in
to your account at http://adwords.google.com/select/login,
and update your payment information.
Of course I got suspicious right away, when I noticed the spelling of ‘stopped’. But, hey, consider yourselves warned.