I've been meaning to write about this for ages. So here goes, better late than never!
Many people, quite rightly, are concerned that sensitive or private data can reside in the metadata of documents created by productivity applications, such as Microsoft Office. To alleviate such potential risks, the Office team created a tool called the Remove Hidden Data tool, which, you guessed it, removes hidden data from documents!
Check it out at http://www.microsoft.com/downloads/details.aspx?FamilyId=144E54ED-D43E-42CA-BC7B-5446D34E5360&displaylang=en.