The site has come online, listing supporters of Open XML. Brian Jones has the details here:

David Carlisle has a post on how Open XML equations and MathML equations can be converted to HTML:  He also added some more information today at

Maarten Balliauw has a great new article on that takes you through creating an Open XML spreadsheet with the PHPExcel API that he and Jakub Vrana have put together: OXD: This sample uses formulas, images, and cell styling.