We recommend that all developers building on Platform test their app against our beta tier. We update this tier daily with the latest changes, before they go into production. For example, next week we will be rolling out some infrastructural changes with how FBML and FBJS work. All FBML Canvas and Page Tab developers should run full regression tests against the beta-tier starting tomorrow (Nov 17th) to confirm that everything is working as expected.
To test against the beta tier just add "beta." before any occurrence of “facebook.com”. For example, you can use your canvas app on www.beta.facebook.com or re-route any Graph API calls through
To check to see if the beta tier has been updated, you can hover over the © symbol at the bottom of the Facebook homepage and compare the last number in the tool tip between the standard and beta tiers. If the numbers are different, it means that you are looking at the beta tier which will be in production after the following push.
If you find any new issues with your app while using the beta tier, please file a bug in our Bug Tracker with detailed steps on how to reproduce the issue and tag the issue with "beta tier". This will help us catch issues before they are put in front of your users. For more information on our beta tier, check out our documentation.