If you are planning to be out of the office and you are subscribed to an eForum with the PDA option (allowing you to respond to messages directly from your email) please be sure to temporarily change your subscription option to something other PDA. Otherwise, your 'Out of Office' assistant will send your out-of-office message to every eForum member, creating potentially hundreds of 'Out of Office' posts in the eForum.
Alternatively, set your 'Out of Office' message's subject line to 'Out of Office.' By doing this, your out-of-office messages will be filtered out of the system.
And remember, it's good email etiquette to only tell people you're out of the office once - so be sure your out-of-office settings are such that you only send people an out-of-office message once :-)