Andy Updegrove has been giving great coverage of all this at his Standards Blog, and writes that Brazil appears to be the leader of the movement, having filed multiple times.
As I noted then Microsoft Office will support the competing, open source ODF format before it supports the final version of OOXML, and this fact is at the heart of the appeal. The company blames changes made by the ISO.
What it means is that as a practical matter there will be two standards for office documents going forward, ODF and OOXML.
It's hard to see executives in fast-growing companies like India and Brazil jettisoning Open Office once the next Microsoft Office comes out over this issue.
It's far more likely that, in many countries, both will be supported, with preference given to ODF where the government's support of open source is strong or a large number of languages have given Open Office significant market share.
What's most frightening, as Paula noted on May 22, is that Microsoft Office may provide weak support for ODF, making conversions difficult.
How much will it cost to build OOXML-ODF conversion tools through Open Office which are better than those Microsoft itself puts out? On that may hang the question of whether you can read your clients' documents in two or three years' time.