We will be making the current experimental version (3.28) the new release version on or shortly after May 16th, 2017. The versions will then be:
3.26 will be deprecated and you will be served an existing version if you try to request it.
If you are using a Premium Plan client ID or an API key from a Premium Plan project, you will be provided with the release version by default. If you are on the standard plan or have no key nor clientid, you will be provided with the experimental release by default.
Please test you application to a the version you will be receiving soon, to ensure the new version is free of issues for you.