Hello there,
Well, it seems that Microsoft decided to quietly release Windows Vista and Office 2007 Beta 2 for MSDN and TechNet subscribers.
By the product keys made available on the MSDN Subscribers download area it seems that Windows Vista Ultimate Beta 2 is available (as well as Home Premium Edition), so it should be packing all the features that have been currently made available.
Can't say more on what are the contents of these releases because the downloads are quite big (DVD images of 3GB each), but a little more information can be found on Microsoft's website (http://www.microsoft.com/windowsvista/default.aspx).
I will be posting back as soon as I manage to install these.