According to the CrossTech blog at CrossRef, Microsoft has released a beta version of their plug-in for marking up manuscripts with the National Library of Medicine (NLM) DTD. The plug-in is called the Article Authoring Add-in. The goal is to allow mark-up by the user/author farther upstream in the content-generation process.
The plug-in can be downloaded from Microsoft now. It is geared for Word 2007.