Have you ever asked the question when researching a property: "Where did the tanks go ?" or "What were the prior improvements ?"  Now Google Earth can help you out with the recent release of Google Earth v.5.0(beta).  A new tool will display satellite images for a parcel for as far back as satellite images exist for the same.    

Once you open version 5.0(beta) and locate a parcel of interest, you will see a tool bar across the top of your screen.  In the center of the tool bar you will notice an icon of a clock.  When you click on the clock icon a dialog box will appear with a timeline displaying the dates of the satellite images Google has stored of your parcel in question.  Slide the marker across the timeline and the history of the parcel is displayed.  

Although with Sanborn Maps  you can typically go back much further in time, having this information at your fingertips can be a valuable resource.