'Tis the season for patent court rulings! Yesterday Microsoft lost an appeal to a patent infringement case for how their Office suite (particularly Word) handles the opening of OpenXML documents. Microsoft made these the default document formats for the latest versions of Office (2007 for Windows, and 2008 for Mac), and as such have been widely adopted.
What does this mean for Mac users? Not much, except that Mac users who run Office might expect an update to their Office suites in the near future, which will change how Office reads OpenXML documents. Microsoft has been ordered to halt all sales of Word that use the old method of opening the documents by January 11th, so they should be hastily working on an update for current and future releases.
The court ruling stated that this only applies to the technologies in Office 2003, 2007, and later for the PC; however, while the Mac is not specifically mentioned I expect Microsoft will be changing how OpenXML is handled in all of their applications.
OpenXML file format is free for anyone to use, and is supported in a variety of Office suites (OpenOffice, anyone?) so support for it in Microsoft Office will not be going away. Overall for Office users this is a rather transparent event, which at the worst may result in a few delays for Microsoft while software gets updated.
Personally, I prefer Pages and Textedit for my word processing needs. For more on the court ruling, see this CNET article.