Hello wshaub,
Thank you for wanting to try Microsoft Codename "Tahiti". Here is a statement from our team about this.
The Codename "Tahiti" project is in pre-Beta, and we are limiting downloads to learn and collect feedback from a small audience. We are very pleased with the initial feedback from the community and are looking forward to making it available for wider use soon.
If you are already running the pre-Beta release, the service will continue to be available. Please check back in mid-April for an update on the official public Beta.
Thank you for your interest!
The Codename Tahiti team