That's why I feel for them, given the flaw that has been found in the Office 2008 for Mac installer. It would seem that the Office installer incorrectly sets some permissions on files, allowing a second local user on your Mac, i.e. a user other than the admin user installing the software, to modify the Office apps and some supporting libraries. This, of course, is not a good thing but the Mac BU has posted instructions on their blog to fix this via some Terminal commands. They also promise that an update to Office will be coming along shortly which will fix the problem for those of users who aren't comfortable in the Terminal.
A great response to an unfortunate mistake, but something tells me TUAW commenters will not be kind to our friends at the Mac BU.