OpenOffice.org (OOO) is offering limited support for Microsoft's OOXML format in the new 3.0 Beta release of OpenOffice.org. This will allow opening of files created by MS-Office 2007 and MS-Office 2008 for Mac in the OOXML files formats for word processor (.docx), spreadsheet (.xlsx), and Powerpoint (.pptx) .
There is no provision to save files from OOO in OOXML, just open them. The files can, of course, still be saved in the older MS-Office formats (.doc, .xls, .ppt), as well as OOO's native ODF format. This could provide a useful open source tool for those needing to deal with incoming OOXML files.
Curiously, OOO's announcement of the release does not mention OOXML, just .docx, .xlsx and .pptx. Perhaps OOO does not want to lend credibility to these formats, or just wants to avoid the controversy over their adoption as standards.