To support the functionality of Identifier Frames, a new data frame extent option, Other Data Frame, has been added that makes it possible to synchronize the extent of your main data frame with the extent of one or more additional data frames. If you pan and zoom in the main data frame it will automatically pan and zoom in the additional data frames. You can use this new extent option to create dynamic locator maps. Additional enhancements have been added to Clip to Shape, Extent Indicators and Definition Queries to make if possible to highlight and display your index area in many different ways.
Also, some of you have concerns about Python. The Python scripts can, and probably should, be depolyed as a geoprocessing script tool. These are tools that are configured with interface that accept input parameters, and run just like a geoprocessing tool. One of the new things in 9.4/10 is the ability to take any script tool and drag it onto a toolbar. So, once you create a tool for say, exporting each map to a PDF, you can add this as a button and no one needs to know that Python is driving it behind the scenes.
Thanks for all the feedback and comments,
David