Microsoft has posted (as of 6/4/2007) a WhitePaper and Presentation that details the deployment of Office SharePoint Server 2007 within Microsoft, including the benefits and lessons learned, which may be helpful to other enterprises considering a large-scale implementation of Office SharePoint Server 2007. For those with ADS, jump to page 24 of the Word document for a great list of lessons learned and best practices.
Note these documents contain marketing fluff but they do contain useful insights from MS IT.