AutoLock is a free automatic key lock application for Series 60. It will turn key lock on after certain amount of time of inactivity.
*Automatic start-up when the phone is turned on.
*Setup tool to change inactivity time.
*It is running completely at the background.
*It is free!
File From: http://my-symbian.com/7650/applications/applications.php?fldAuto=826&faq=2