Microsoft Office
Home page: http://office.microsoft.com
Status: 
Microsoft Office is an office suite developed by Microsoft. It has a dominant position in the office suite market largely through the use of closed proprietary formats.
Reviewer: Daniel Carrera
Review method: I have not tested the ODF plugin directly, but a basic test by Rob Weir shows that the plugin has a long way to go.
Notes: Support is not available yet. Microsoft has announced work on a plugin that will allow MS Office to read and write OpenDocument files. This plugin must be downloaded separately.
As of writing, this plugin can convert some OXML files into OpenDocument (OXML is the native format of Microsoft's up-coming Office 2007) but cannot convert any OpenDocument files into OXML.
Comments
An MS Office plugin for OpenDocument would a large barrier to OpenDocument adoption. Microsoft's dominant position in the market makes it difficult to use a format which they do not support. The fact that Microsoft is adding support for OpenDocument now shows that there is a strong customer demand for it (notably from governments).


