Today not only marks the release of a new beta Remote Desktop client from Microsoft, but also a new beta Microsoft Office Open XML File Format Converter for Mac 0.2 (Beta). What the heck is this? It converts Office files that use Microsoft's new Open XML file format (i.e. files created in Office 2007 for Windows) into a file format that Office 2004 for the Mac can read. This release promises improved conversion of files containing inline graphics, amongst other things.
Since this is a beta Microsoft warns that all files might not be converted correctly. They suggest you open the file and make sure it looks like it should.
Update: As was pointed out in the comments, this only converts Word and PowerPoint documents.