Paul,
The closest thing to what you are looking for is the variable ##LastNoteUser##. Other variables pertaining to notes are ##LastNoteDate## and ##HasNotes##.. Typically, if I want to see what variables might be available for a given request, I'll invoke the following web service:
http://localhost/esd/ws/integration.asmx/GetResolvedRequestVariables
Sometimes you may find something of interest...