250px-Multicast_svg Well, I was just going to write a post on one of the coolest features in Windows Server 2008 - Multicast Deployments (aka the ability to image multiple machines in parallel).  However, I see that TechNet Magazine covered it last month!

http://www.microsoft.com/technet/technetmag/issues/2007/05/DesktopFiles/default.aspx

The WDS team has changed all that by delivering a new multicast engine that takes advantage of the file-based Windows Imaging Format (WIM) infrastructure to allow for some very unique capabilities. You can perform the same staged multicast scenarios possible with most third-party multicast software, but the multicast solution for WDS delivers much more.

First, client computers can join at any time in the transfer. The multicast broadcast is a "round robin" broadcast of file streams that will continue to broadcast until every client computer's needs have been met. Because of this, it doesn't matter when clients come online. They listen to the WDS server, and when the server has completed the image file broadcast, it starts over from the beginning. If a client misses a file, it just listens until the file comes around again (think of horses on a carousel).

Second, the protocol is completely new and features congestion control and flow control—meaning that it works well on production networks without interfering with existing network communication. A common fear of network admins—justified with some multicast solutions—is that by turning them on you flood the network with traffic when, ironically, you were actually trying to make communication more efficient.

Third, the solution was designed to be independent of WDS and Active Directory®. This means you do not need to have either Active Directory or an active WDS implementation in order to take advantage of it. ImageX multicast can be performed independently, lending itself to many more scenarios. The multicast client is a command-line application that can run within Windows Server "Longhorn" (and its associated release of Windows PE), Windows Vista™, Windows XP Service Pack 2 (SP2), or the recently released Windows Server 2003 SP2.

There are new management tasks in the WDS MMC and in the WDSUtil application to set up and configure multicast. There is also a change to the user interface of the WDS client indicating that multicast is being used.

The WDS management tools allow administrators to monitor real-time transmission progress to clients (including removing clients from a transmission). The management tools also offer full logging and reporting, meaning that administrators will now have a method to log installations—something that RIS was sorely lacking.

If you will be installing Vista to one or two or 5 computers at a small business, then multicast deployments are probably not a big deal for you.  If you will be working on a large-scale rollout of Vista (you will be working on large-scale rollouts of Vista, won't you?), or work in an environment where computers are routinely re-imaged (as is the case in many Governmental or Security-focused organizations) then multicast deployments were previously only available with 3rd party imaging tools.  With the advent of the Windows Imaging Format (WIM)- based OS deployment images, Microsoft has a top-notch imaging format (with several awesome capabilities such as non-destructive image application and single-instancing of files).  Add on the Multicast deployment capabilities of Windows Server 2008, and the OS deployment story becomes much more compelling.  Throw in the Windows Vista Hardware Assessment tool (which will scan your network, give a breakdown of what machines are/are not able to run Windows Vista, writes a customized report for the Business Decision Maker (complete with charts!), along with a spreadsheet listing an inventory of all computers on the network...  All of this with built in (or freely downloadable) tools included with Windows Server 2008.  I'm not even going to touch the SMS/SCCM OS Deployment Feature pack that allows you to REMOTELY install/upgrade computers to Vista...

In a previous life, I was responsible for deploying/upgrading hundreds and hundreds of Windows XP installations at a Fortune 500 company.  The above tools would have GREATLY simplified my job.  Good times :)