Yes it is totally sanctioned Beta 2, with RC1 to follow. You can order the DVD's or d'l here:

http://www.microsoft.com/windowsvista/getready/preview.mspx

While that looks like a totally benign link, if you scroll down it gives you options to order the DVD or download. The download manager is totally horrible because it doenst auto connect after an error, which happends about every two minutes....but can you imagine the amount of people trying to d/l this??