There is no URL for this. The Beta1 is all that's been "semi-publicly" released. It was only released to a select few people though, including those who attended the last PASS conference I believe. They have not posted it on any websites though.
There is a post-Beta1...pre-Beta2 also, but only the SQL Server team, MVPs, and a few select Beta testers have it. They are required to sign an NDA and won't share it. (Trust me on this one. lol)
The Beta2 release is supposed to come out sometimes within the next month or so. It will be publicly available.
Until then, you can see information for Yukon at:
When life gives you a lemon, fire the DBA.