Both Doug Mahugh and Eric White have some info on this, version 2.0 of the SDK for Open XML is now available as a CTP, you’ll find it here.
Some of the new features include;
Sphere: Related ContentThe OpenXmlDiff utility identifies differences in the markup in two Open XML documents.
The Open XML Class Explorer helps you determine which strongly typed class to use for a specific task, and includes the text of the relevant section of the ECMA-376 spec for each class.
The Open XML Document Reflector takes a target document as input, and with a few clicks it shows you the C# code needed to generate that document (or a section of it) with the Open XML SDK. This tool will be a huge time-saver for those who need to write code to generate documents to match a template defined by others.