I'm not sure of a couple of things... is this only for people with MSDN access, or a 100% public beta such as they did recently for office 2007? What restrictions will be placed on it (I'm going to guess it'll be expireware)? Etc etc.
On the other hand, this is pretty brilliant. Vista is the "next big thing" for the home desktop market, and all the magic 8 balls say that it'll be available to the public Q1 2007 at the earliest. That's another 6 months before it can start being realisticly in the hands of the average joe, and then only at either the cost of the OS or bundled with a new computer. This way everyone can get access to it, free, get the brainshare going, and have an extra 6 months of (in theory) training to get used to the OS which will be a lot different than XP.
I wonder if they'll be taking tech support calls, or will be relying on the QA software built into the OS itself? Either way, it'll be interesting to see if this makes the final release less buggy and more secure.
Also, it kicks the pirates in the balls a bit. No more need to download the torrent from pirate bay, grab it straight from MS. Of course, this also goes along with my theory that MS actually likes pirates or at least does the minimum to protect their software from piracy so it gets into the hands of the most people, and increases their brainshare. Now, they have been cracking down lately, but when you have 90% of the market, you don't need to spread much further.
Things I'll be looking for...
Anyway, I'll be downloading and installing this over the vista beta 1 install I have from an earlier torrent on my second hard drive :)
Update: Downloads now working.....