URL of the news:

Microsoft has released a roadmap for the Open XML Software Development Kit. The Open XML API will be released in two versions. Version 1.0 would include an updated version of the CTP that was released last year in June 2007, to be released in April 2008 with a final release of Version 1.0 in May 2008.

Version 2.0 will be available as a CTP version this summer, and the final release will be part of the Office 14 wave of products and technologies. These include all parts of the Open XML API architecture with Word processing ML, Spreadsheet ML, and shared Presentation ML. Both versions are available as free downloads from MSDN at the Open XML SDK page.

 Source (http://openxmldeveloper.org/archive/2008/03/13/OpenXMLSDK.aspx)