Unfortunately I think that this campaign cannot be joined by mobile phone users because it’s damaging them. None of the mobile operating systems I have stumbled upon offers support for OO.org. Maybe on Android there is a way to read attached ODF files, but through Google Docs (support of Impress file format is missing, though). ODF support on BlackBerry was announced but I couldn’t find mention on their website. I think Meego (formerly known as Maemo) has native support for ODF, but very few people use it. Not sure about other OSes. A search for OpenOffice.org/ODF on Nokia Ovi Store produced no result. That alone excludes 40% of European mobile phone users (millions of people, including me) from joining this campaign. I wish I could join this campaign, but for me is still impossible to view an .odt or .opd on the move, so I prefer to receive a .doc or .ppt that I can use on my OpenOffice.org desktop and also look at it on my phone.
Mobile users still have too little freedom to reject proprietary formats. For Document Freedom Day I would like to add a new item to the FSF’s list of priorities: support for ODF on mobile operating systems, from Android to Symbian to others.