Kahena first discovered that Google was blocking access to their AdWords API on tools like SEOmoz and Raven.
Pamela from Search Engine Land received confirmation from Google that they do review and audit usage of the API and take action when necessary. Google said:
We regularly audit developers to make sure they comply with the terms of our AdWords API so that AdWords customers get the best experience when they use third-party applications.
Here is a screen shot from Kahena of SEOmoz stating the limited functionality issue:
Pamela also has statements from both SEOmoz and Raven:
"We would like to tell you more, but it wouldn’t be appropriate," wrote Raven communications director Arienne Holland in a blog post. "What we can tell you is that Raven is committed to providing data from Google, and we're continuing the conversation with the AdWords team."
And SEOmoz product manager Tela Andrews wrote, "Google hasn't given us specific feedback on features that led to our credentials being removed. Without specific guidance, we would rather focus our efforts on getting replacement data from other sources."
Forum discussion at WebmasterWorld.
Update: Seems Raven has been restored.