Microsoft as announced the availability of Open XML Document viewer plug-in for FireFox. This provides a light-weight way to view OOXML document (i.e. .docx, .xlsx, etc) documents from within FireFox.
These plugins are available from Codeplex at: http://www.codeplex.com/OpenXMLViewer. This page has a good description of the high level architecture, a cool-ish 4-minute video demo of the translation and the FireFox plugins. There’s also a link to the download, including viewers for Windows and Linux versions of FireFox.
The Windows download is fairly big – 3.5MB – indicating the complexity of the underlying code. To install the plugin, just expand the .ZIP download and drag/drop the XPI to FireFox, restarting FireFox to complete the installation. After installation, it looks like this:
The viewer is a CodePlex project (and not a formal Microsoft project), and the videos are YouTubed not available directly from Microsoft. An interesting approach – pragmatic to say the least (plus google gets to pay for the bandwidth used to view the videos).
Also, these viewers are at present just a Community technology Preview and not fully ready for release. Final release will come in the spring of 2009.