Timestamping print from ArcReader?

"The Publisher Map Title is a single text element" so try putting some dynamic text formatting into it like:

Date: <dyn type="date" format="dd MMM yy"/>
Time: <dyn type="time" format="HH.mm.ss"/>

Do this before you publish the map and it should carry through to the PMF.

Only by using an OLE Object (MS Word with Date and Time) when published the object becomes static.

http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#/Map_Contents_Summary/000s00000011000000/