Finally! Microsoft has wizened up and decided that as Save as PDF option is pretty handy. And to think that OpenOffice and even Google Docs have had the feature a long time ago. Anyway, straight up, this thing adds a Save as PDF or XPF option in your Save As menu. And depending on your choice, Office will be saving the document in that format.
Note that you need a valid Office 2007 installation to get this plug-in from the site. Otherwise just try your luck with Google search to get a direct download link without the validation. I’m pretty sure some people have found a workaround.