I imagine sharing IP addresses across apps and cloud computing go hand in hand and this is not limited to GAE.
No, that is not necessarily the case.
If I'm sharing an IP with another Mailchimp user and their app is misbehaving, why are you not blocking their API key rather than the whole IP for both of us? There may be a valid reason - I'm trying to understand the issue.
We didn't block anything based on API usage. Had we, either we'd shut off connectivity completely, shut down the offending account(s), or disable the API key(s) involved - all of those things have been done.
I would also point out that your error message in this situation is confusing and states that the API key is invalid or something to that effect.
Abuse scenarios are often met with vague responses. What was the scenario? No clue, but again, the previous thread covers ways to have it investigated.
jesse