There are a number of Adwords advertisers who have received an email like this:
Dear AdWords Customer,
Your ads have stopped running because we were unable to process your billing information. To activate your account and start running your ads, enter your billing information.
In order to activate your account and start running your ads, enter your billing information. Pease sign into your account athttp://adwords.google.com/select/login, and update your billing information.
Once your account is reactivated and your billing information has been processed, any your ads and campaigns can begin running immediately on Google.
The Google-AdWords Team
Be warned – this is likely an effort to get your credit card. Google doesn’t send out emails like this. The clearest way to check if this is a scam is to view the hyperlink properties in the login url (changed above to go to the actual GG login). Typically it will show a target url that is not Google.com.