Microsoft announces that it will expand the formats supported by Office.

The 2007 Microsoft Office system already provides support for 20 different document formats within Microsoft Office Word, Office Excel and Office PowerPoint.
With the release of Microsoft Office 2007 Service Pack 2 (SP2) scheduled for the first half of 2009, the list will grow to include support for XML Paper Specification (XPS), Portable Document Format (PDF) 1.5, PDF/A and Open Document Format (ODF) v1.1.

When using SP2, customers will be able to open, edit and save documents using ODF and save documents into the XPS and PDF fixed formats from directly within the application without having to install any other code. It will also allow customers to set ODF as the default file format for Office 2007. To also provide ODF support for users of earlier versions of Microsoft Office (Office XP and Office 2003), Microsoft will continue to collaborate with the open source community in the ongoing development of the Open XML-ODF translator project on SourceForge.net.

In addition, Microsoft has defined a road map for its implementation of the newly ratified International Standard ISO/IEC 29500 (Office Open XML). IS29500, which was approved by the International Organization for Standardization (ISO) and International Electrotechnical Commission (IEC) in March, is already substantially supported in Office 2007, and the company plans to update that support in the next major version release of the Microsoft Office system, code-named Office 14.
Via this Microsoft press-release.