Yes, just yesterday we posted a Flamingo 5.5. This is a version of Flamingo NXT 5 that runs in Rhino 5 and Rhino 6. The installer will install for both.
You can install it by installing Flamingo off this link:
The Rhino 6 compatible version of Flamingo NXT will be included with the current Flamingo NXT 5.
The Rhino 6 version is still quite rough. We are working to catch up with the new rendering framework in Rhino 6. Please report any problems you have. We will update it often over the next few weeks. I also expect some of the issue you find we will need to see Rhino 6 fixes in.