If you're embarking on a Windows 8 migration -- or even if you're in testing mode for the time being -- you'll want to download the Windows Assessment and Deployment Kit (ADK) for Windows 8.
This free download includes a number of tools and utilities worth exploring. For starters, the ADK for Windows 8 rolls up a number of previously released tools into a single package. These include Deployment Imaging Servicing and Management, Windows System Image Manager, Windows Preinstallation Environment.
A significant number of additional tools are included as well to help you customize your Windows images with the settings and applications tailored to your environment.
If you use custom deployment images now, you probably already know about the Deployment Imaging Servicing and Management (DISM) tools. These are absolutely essential for updating your Windows images with the latest patches and such. For managing Windows 7 images you should read this article on Technet. The Windows 8 version can be found here.
For unattended setup on new machines, you'll need to learn how to use the Windows System Image Manager (Windows SIM). This would be the best way to do an unattended installation on machines where you don't have a pre-built image. In some cases you might need to use this method to make sure the proper drivers are loaded for each unique machine. It basically allows you to create an answer file, which you can edit to add any additional steps for your environment.
The Windows Preinstallation Environment (Windows PE) is basically a minimal operating system (OS) used for an initial boot to do things such as partition and format hard drives, copy disk images and launch Windows Setup from a network share. This tool is particularly useful for large distributed organizations looking to roll out OS upgrades without having a technician visit each individual machine. Many, if not most, modern systems will remotely boot into Windows PE as a BIOS option. Windows PE 4.0 is based on the Windows 8 operating system.
For the planning stages of deployment you'll find tools such as the Application Compatibility Toolkit (ACT). This tool is similar in functionality to the MAP Toolkit in that it uses an inventory collector to gather information about applications currently deployed in your organization. It will collect system, device, and software information from specifically targeted computers. The ACT information page on Technet describes the different types of systems you should target when using this tool.
When you get down to actually migrating users, you'll want to use the User State Migration Tool (USMT) to move individual users' information, such as application settings, bookmarks, and system preferences. The goal of this tool is to make the user transition as seamless as possible.
The big message here is you need to run these tools in a controlled setting to understand how they work in your environment. Now's the time for your IT teams to get started on your pilot projects if you want to stay ahead of the user demand.