WES 2011 images are no longer build on the development machine, but are configured on the target machine using a template or a custom unattended.xml configuration file. Due to this, there is a new important thing embedded OS developers need to get used to: configuration passes.
They describe the different phases the OS setup routine needs to go through while installing the image, preparing the hardware or even doing offline servicing.

Here is an overview :

• windowsPE
  Configures Windows Preinstallation Environment (Windows PE) 3.0 options and basic Image Builder options. These options can include setting the product key and configuring a disk.
• offlineServicing
  Applies updates to a Windows Embedded Standard 2011 image. Also applies packages, such as software fixes, language packs, and other security updates.
• generalize
  Minimally configures sysprep /generalize and configures other Standard 2011 settings that must persist on your reference image. The sysprep /generalize command removes system-specific information. For example, it removes the unique security ID (SID) and other hardware-specific settings from the image. The generalize pass runs only if you run sysprep /generalize.
  specialize
  Creates and applies system-specific information. For example, you can configure network settings, international settings, and domain information.
• auditSystem
  Processes unattended settings while Standard 2011 is running in system context, which occurs before a user logs on to the computer in audit mode. The auditSystem pass runs only if you start in audit mode.
• auditUser
  Processes unattended settings after a user logs on to the computer in audit mode. The auditUser pass runs only if you start in audit mode.
• oobeSystem
  Applies settings to Standard 2011 before Windows Welcome starts.

There is great flexibility as well as some challenges introduced by configuration passes. On the one head the possibilities to influence the operating image are absolutely fascinating.
For the first time, there is an end-to-end tool chain available for bringing up bare metal embedded devices or upgrading field systems unattended, now. On the other hand, is it required to understand when to change what setting to get the desired result in the final image. 

To shed some light on the magic of configuration passes, my next posts will drill a little bit deeper into each one of them.

Alexander