Rhino 5 automatically downloads service releases to your computer and notifies you when they are ready to install. You can control when updates are downloaded in Rhino Options > Updates and Statistics. You can also download them from here.

For pre-release builds, under Rhino Options > Updates and Statistics select:

• Weekly to automatically download pre-release builds of Rhino that contain the most recent fixes and enhancements. These builds are tested by McNeel testing staff for stability and reliability, but may contain bugs that we haven't discovered yet.
• Service Release Candidates to automatically download pre-release builds that the development team believes are stable, reliable, and are ready for broader testing.

A new Wishlist forum has been added on the Rhino 5 community site to help manage the ongoing wishlist discussions.

Labs projects are plug-ins for the current version. They are early prototypes of features that may or may not be in the next major version. Please download them, use them, and provide feedback. The current labs projects are here...

A real OS X version Rhino 5 is in the works. It is an ongoing process and is being released in phases. During the pre-release phase everyone is invited to give it a try. At first release, Rhino 5 for Mac will not be on par with Rhino 5 for Windows, during the first release phase, there will be many enhanced and bug fixes. Pre-release builds will still be available to licensed users and all of the Rhino 5 for Mac will be free.

We need feedback from both expert and novice Rhino users. We are willing to spend whatever time and effort it takes to get it right, but we need you to tell us what is wrong. During development, pre-release Rhino for Mac is free to anyone willing to provide feedback. Details...

After Rhino 5 ships, Rhino 6 pre-release builds will be available to Rhino 5 users in phases:

• Work-in-Progress (WIP) builds include prototyped new ideas and technologies. WIP builds (often called Alpha releases) are not production ready, and some ideas and technologies may never be released. Rhino 5 users will be invited to get involved. Your feedback at the WIP stage has the most impact on the design of the features and enhancements.
  
• Beta: Once most of the core changes are finished and tested, beta builds are released. The beta builds should be production stable but may not have all the features or user interface finished. 
  
• Final: We release a new version only when the beta users tell us it is ready. Beta users are informed when we have stopped development and have released Rhino 6 to production.

Notes

• All Rhino 5 users will be invited to participate in the Rhino 6 development process. There is no charge.
• Each phase normally takes more than 6 months.
• Each WIP and beta builds expires every few months. A newer build is always available before expiration. This ensures that bugs are reported for the latest build, and that we don't receive reports for bugs that are already fixed.
• The final beta release will not expire for at least two months after the new version starts shipping.