Oh you mean the shape area of the feature? If you want that as you are working in ArcMap, that would have to be ArcObjects.You could write a script that does that if you just want it for exporting. I've never tried it with data driven pages before, here's a bit of code to get you on the path.for page in export_loop:
layer = "data_driven_layer"
ddp_field = "Field_Name"
desc = arcpy.Describe(layer)
shapeField = desc.shapeFieldName
where = "%s = '%s'" %(ddp_field,ddp_value)
s_cursor = arcpy.SearchCursor(layer,where)
for row in rows:
page_area = row.getValue(shapeField).area
for elm in arcpy.mapping.ListLayoutElements(mxd, "TEXT_ELEMENT"):
if elm.name == "Dyn_Area":
elm.text = page_area
Edit: What Darren said below. My suggestion would be more use accessing other layers attributes based on the current data driven page.