Vault Professional 2015 R2 and Vault Workgroup 2015 R2 have been posted to the Autodesk Subscription Center under "Product Enhancements".
See whats new in Vault 2015 R2 here
You can review the readme here
Vault Professional users BE AWARE, some functionality has been removed which can impact workflows and 3rd Party Integrations. Details can be found in the readme.