Thanks to scoop
"Hold the front page" another beta has sliped the net. This time is .Net Server build 3660
This is an interim build between Beta 3 and RC1 is not considered "Beta quality". This build is intended as a preview of our progress post Beta 3 and to allow us to verify the build quality as we approach RC1. We do not require that you install this build. If you choose to install this build it is recommended that you back up all data and configuration information prior to installation.
UPDATE: The Inquirer has got hold of some more info on this build. And what looks thike the full readme for this release.
Screenshot: .Net 3660 Download