I'm afraid there's no record of this (by default) as as Brian has mentioned.
That said, you could probably force such a detection if you use Application and Device Control in your environment. All you'd be looking for are "File and Folder Access Attempts" to read the below file:
C:\Program Files (x86)\Symantec\Symantec Endpoint Protection\12.1.3001.165.105\Bin\SEPOutlookAddin.dll
Or just SEPOutlookAddin.dll on its own will also work. The A&DC rule should get triggered everytime Outlook is started (and loads the dll). Unfortunately, it does require you configure your AV policy to enable the Outlook Plug-in though.
As it's just informational, I'd just leave the rule in Test Mode. Look for the logs on the SEPM Console afterwards for which machines are using it (MONITORS -> Logs -> Log Type: Application and Device Control -> Log Content: Application Control).
This file does not exist on machines without the Outlook bit installed, and this is for SEP12.1 (might be a different dll in SEP11).
#EDIT#
Oh yeah, this is all working under the assumption you only have access to the SEPM. A logon script with a "IF EXIST" check for the above file is going to be easier if you can create a GPO or something, and make the machine(s) write their hostname(s) to a share.