Google Docs will stop supporting the export of old Microsoft formats next year.
According to a previous announcement, Google announced it would stop supporting Microsoft Offie formats 2003 and earlier such as doc, xls, ppt in late September.
However, Google users have requested more time, so Google moved this deadline until December 31, 2012. This was confirmed by Google Enterprise president, Amit Singh, on Google+.
Since that time, Google Docs will support exporting to open standard Microsoft Office formats (docx, xlsx, pptx).