When it's ready:)
or
Soon™ ( Sorry for not being more specific ) Unfortunatly it was delayed because we've prioritised the task to make it available for self hosted clients, before we ship any new Zapier features.
That said, we've enhanced some existing REST API endpoints and have added few new webhooks for the next release of the suite, which are required for our new Zapier triggers and actions, which are coming along other many under the hood improvements.
I really can't wait to share all the new stuff with you!