The Microsoft Dynamics AX 2012 SCM code upgrade white papers have been available for download on MSDN. Enjoy!
Implementing InventTrans Refactoring - Discusses the refactoring of the InventTrans table and common design patterns. Also discusses how to implement these changes when developing new features or updating existing features.
Implementing the Item-Product Data Management Framework - Highlights the new patterns that are used to represent item-product master data. When detailing the new patterns, the document also describes the pattern that is being replaced and how developers should approach updating their code.
Implementing the Operations Resource Model - Describes new patterns that are used for representing resources, resource capabilities, and resource groups, and provides instruction for upgrading and implementing the new operations resource models.