Yesterday we talked about rolling out our throttling based on User-Agent strings. A few minutes ago we pushed this feature live on our servers so now the updated rules are in effect. python-musicbrainz/0.7.3 users are now allowed 500 requests every 10 seconds and every single one of these requests is constantly being used. No surprise here. 🙂
For the exact details on what is throttled and how to get around your application being throttled, see our rate limiting documentation.