The Open XML SDK was released today under the Apache 2.0 license
The Open XML SDK provides open-source libraries for working with Open XML Documents (DOCX, XLSX, and PPTX). It supports scenarios such as:
High-performance generation of word-processing documents, spreadsheets, and presentations
Document modification, such as removing tracked revisions or removing unacceptable content from documents
Data and content querying and extraction, such as transformation from DOCX to HTML, or extraction of data from spreadsheets
Copyright (c) Microsoft Open Technologies, Inc. All rights reserved. Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
It would be great if in near future LibreOffice (or other open source project) will be 100% compatible with MS Office. A lot of people can not get rid of Windows becuse of MS Office. I think it is a reaction of Microsoft to cloud services from Google (Google Docs).