An article on the dangers of not removing embedded change-tracking and metadata from Microsoft Word documents:
I happened to be browsing aimlessly through case studies and other publications released by Microsoft [...] I stumbled upon a Word file I wanted to read [and] noticed there is a good deal of amusing change tracking information still recorded within the document. [...]
A pointless idea came to my mind that instant: why not run a gentle web spider against all Microsoft sites in English, specifically looking for other instances of tracking data not removed from documents?
Another, in a legal context:
[...] how a Microsoft Word document of SCO's lawsuit against DaimlerChrysler indicated that a lawsuit was also contemplated against Bank of America.
Incidentally, Microsoft provides a downloadable tool to remove all hidden data from Word, Excel, and PowerPoint files (they're all vulnerable), but only for Office 2003 and XP on Windows.
Manual methods of removing the information for those versions of Word (and earlier ones) are also available.