If you use the Time Sheet feature there’s a way to track which time sheets have not been “signed” and/or “approved”.

Reports > Employees > 03.73 Time Sheets Not Signed 

Pull up time sheets that have not been “Save / Sign” by the employee yet.  The starting and ending date both pull from the time sheets from (starting) date. Ex. If you are checking on time sheets dated 10/29/2012 – 11/04/2012, then you can use both starting and ending dates on the report as 10/29/2012. 

Reports > Employees > 03.72 Time Sheets Not Approved 

Pull up time sheets that have not been approved by the supervisor yet.  The starting and ending date both pull from the time sheets from (starting) date.