I know there is a lot of chat around the Web, regarding the availability of "7" on the partner site. I am a regular visitor there and have seen no mention of it on any of the pages.
It is quite easy to become a partner, if you can refer, in the application, to a registered company, but there are various proviso's in the small print which could still prohibit you from receiving full information on downloads.
As far as I know, the Windows 7 version which is circulating illegally at the moment, is for Ms worldwide interoffice use. It is basically the updated Vista, with a few already added , but minor functions. I would imagine that when it has reached a stage when there is something to test, it will be released to newly chosen Beta testers.