Example: Update Text Element in Map Document
mxd = arcpy.mapping.MapDocument(r"C:\GIS\TownCenter_2009.mxd")
for textElement in arcpy.mapping.ListLayoutElements(mxd, "TEXT_ELEMENT"):
if textElement.text == "GIS Services Division 2009":
textElement.text = "GIS Services Division 2010"
arcpy.mapping.ExportToPDF(mxd, r"C:\GIS\TownCenterUpdate_2010.pdf")
del mxd
The geoprocessing arcpy.mapping module is intended for use by anyone who needs to automate an ArcMap work flow.