Laughably Microsoft are asking British citizens to sign an e-petition backing their (not)Open Office XML document format! Don’t sign it but do go sign the petition calling for Open Document Format (an actual open document standard) to be used by the UK government. And tell your friends to do it too.
This is important, governments are the keepers of records of last resort and if those records are not in a published and open format then the possibility exists that in the future these records may not be editable or even readable (have you tried opening a Word 5.0 document recently?). That document formats should be inter-operable and conform to an open standard seems obvious to just about anyone if they stop and think about it for a moment, sadly OOXML from Microsoft is not nearly as open as the title would suggest.
Keeping the format closed (whilst pretending it is open) serves only to maintain vendor lock-in. This is the information age and you should take steps to ensure that you own your data, not anyone else!