I get this console log message about every 5 minutes and I suspect it is from iStat Menus

Dec 28 07:07:41 Kelekona SystemUIServer[176]: running on battery - smart disabled

Thing is, I'm not running on battery. I'm on a MBP running OSX 10.5.6. The problem has been there for some time though and is not new to the 10.5.6 update. In the interim I've unchecked the option in iStat to not check SMART status when on battery power and I'm no longer getting the log filling warnings.

Based on my google searches, others are seeing the same behavior.

I can provide additional details if needed.