With Civil 3D 2012 users will now have more intuitive and automatic tools to manipulate volume surfaces. If you remember, Civil 3D had tools for elevation banding, but the entire process was very manual and time consuming. It involved manually adjusting colors for datum above or below. Now when doing surface analysis, you will notice that there are more options. With this users have more control when it comes to view the surface analysis. This is how the options were in Civil 3D 2011:
This is how it looks now:
This option is also very useful when working with Volume Surfaces so that the resulting style can be set as cut or fill. In the following image you may see the additional options and how to set the datum elevation to display cut/fill. Note the existence of Reset button next to Run Analysis button.
So to run analysis on Volume Surface, you would need to set the Analysis Type to Elevations, select Range interval with datum, set Datum elevation to 0 and click reset button. That is all it takes. Final result will be a nice volume surface clearly showing cut and fill areas of the surface.