Apple has released a downloadable update that will give iPods a volume limiter. The volume limit will allow aparents to set a maximum volume on an iPod and lock it with a combination. The update is available for the iPod nano and iPod video.
All this, of course, is a result of a law suit by John Kiel Patterson, who is suing Apple. He claims that his iPod is generating more than 115 decibels, a dangerous noise level.

I vote instead of adding a volume limiter, Mr. Patterson stops being a dumb ass and just turns down his volume.

Apple puts limits on iPod levels [BBC]