If you're using Windows SharePoint Services (which is installed with Team Foundation Server) or SharePoint Portal Server, you don't get to see the file icons for the files with Office 2007 extensions (i.e. docx, xlsx, pptx, etc.)

I'm not sure if they have updated it in the 2007 version of SharePoint Portal Server, WSS 3.0, or in TFS 2008.  If you happen to know, contact me and let me know and I'll update it here.

Anyhow, have you ever wondered how to add new file extensions with associated icons into SharePoint?  Check out the blog site that Alexander Groß manages and he has just how to do it!  It's something that has bothered me enough already and I'm ready to get it resolved!

How To:  http://www.therightstuff.de/2006/12/16/Office+2007+File+Icons+For+Windows+SharePoint+Services+20+And+SharePoint+Portal+Server+2003.aspx

Ed B.