Noooxml.org has just grouped together some thoughts and a summary from Groklaw. These show how serious a consideration patents must be when it comes to using or implementing OOMXL. From this detailed overview:

Patent licensing is probably the most important aspect for all third parties that want to implement or use the Open XML specification. Unfortunately the Ballot Resolution Meeting cannot discuss these aspects because only technical and editorial issues would get resolved.

[...]

When you have a patent which covers Open XML and you refuse to license it, the standard process gets stalled. Large companies in the standardization process are reluctant to use that nuke option. Given the ambush that the software patent practice means today it is quite possible that Open XML infringes a patent and all parties eventually have an obligation to license it.

You are also encouraged to watch the following video presentation which highlights a few of the key issues, including the one cited above.

When watching this, remember that only Microsoft seems to be involved in preparing OOXML. This fails to address and even contradicts the requirements of open standards. Also, publicly available information is needed for scrutiny, but ECMA and Microsoft use passwords as barriers.

Other points which the speaker raises are non-discriminatory and fair conditions in implementation of standards. They facilitate real competition and choice, which makes better products and reduces cost. These are just the classical and usual arguments for real open standards. For those in search of a primer, the video might prove handy. ⬆