These changes will be effective starting with the release going out today. (The other changes we're making in the current release are minor and should have no impact on the API.) We will include the default versions in our blog post for each release. This week's versions are:
Current Release: 1.28
API Default: 1.27a
As always, we value your feedback. Feel free to post comments on the API discussion group as we'd love to hear from you.