I'm often asked lots of questions about how Microsoft runs SharePoint. I think a cynic's view of the product is "What would Microsoft have to create to allow all 140,000+ employees and contractors to collaborate and search for content? And the answer is SharePoint", and that may not be far wrong. In any event, we run into the same problems our customers run into when trying to balance flexibility for rapid site creation -- anyone can create a SharePoint site collection -- balanced with information security -- confidential information is housed appropriately -- balanced with operational efficiency where the sites are well-maintained and archived/deleted when no longer needed.
Earlier this year, Microsoft IT published a white paper which discusses the custom solution we use to address these issues: http://technet.microsoft.com/en-us/library/hh305231.aspx -- Implementing SharePoint 2010 Site Governance and Lifecycle Management. Completely by chance, I happened to find a free seat at a table during breakfast on the last day of the Sharepoint Conference in Anaheim and ran into the presenters for a session on this topic. Always fun to meet the folks you have heard about and work for the same company because of some random event like a free seat nearest the buffet line!