Microsoft still don’t get open standards – their new OpenXML office file format is patent encumbered, but not in a way that is obvious. Sam Hiser has an interesting evaluation of the license for OpenXML and it appears that whilst MS do promise not to sue you for any patents that cover anything that is explicitly in the specification they do not do so for anything that you need to implement that specification.
We know of a great deal of Microsoft technology which does in fact contain patents and which lies outside the specification which would need to be implemented by such a 3rd-party for the formats to work. The Microsoft Office Open XML formats are therefore dependent upon a host of patented Microsoft technology.
In effect, this license means that if you are making a well-functioning, complete implementation of the Microsoft Office Open XML specification, then you are not covered by the “promise” in the License. In other words, Microsoft effectively prohibits you legally from making a complete and working implementation of its new formats in your software. If you do, you run the risk of being sued.
In other words, here is an open specification that you can only implement if you either (a) are willing to get sued, or (b) lucky enough not to live in a country that has stupid software patent laws..