Where can I find system log information on OS X Lion 10.7.5 for System Preferences changes? Suppose I navigate to System Preferences and make a simple change (say I turn off BlueTooth).  

Is it logged somewhere in the syslog? In other words, is there a log file somewhere on the file system that keeps track of what was written to the System Preferences plist file?

The main reason I am asking this question is because I would like to know when certain things were set in the System Preferences.
You can find that information in the ~/Library/Preferences/com.apple.systempreferences.plist

They will open in TextEdit, but hard to read. So you might need to read this for help with Plist readers.

you can also see the plist changes in the:

Console (by typing pref in the search window)



While the Console is up to the moment reporting it will only report issues not the successful execution.