As mentioned here Rhino 6 WIP (work-in-progress phase) would be available to users who purchase Rhino 5 license. A recent search of mine turned with no results for downloading the WIP software. But a quick Google search leads us to this page where the change log of Rhino 6 WIP (10/21/2014) is announced. However, download button on the page redirects to the main download page of Rhino3D.com.Please comment if you have news about the development, and keep following the post for others' replies.
EDIT:
This help page shows what is new for now in Rhino 6 clearly:
http://docs.mcneel.com/rhino/6/help/en-us/commandlist/newinrhino.htm

Hi Ozkan,
ReplyDeleteYou can try to download it from link below:
http://www.rhino3d.com/download/rhino/wip?PageSpeed=noscript
Thanks,
Taghi