The company has published rules of use for the logo at https://adwords.google.com/select/AP_Terms.html. The logo is only available to those who have passed an exam, who have at least one or more accounts through My Client Center for 90 days and who spend at least $1,000 per month via those accounts. There's also a $50 exam fee, which Google says goes entirely to the company managing the test.
Interestingly, only individuals can be considered certified by Google, not companies. This means that search marketing companies will have to be careful to say that they employ qualified Google Advertising Professionals, not that the companies themselves are qualified. Google said a company certification is something it may consider for the future.
