The AirPods will support up to five hours of battery life on their own, and apparently, built-in sensors know when you remove them from your ears to help save battery. They come packaged in a case with a built-in battery that will keep them charged for 25 hours. The case itself, which looks like a pack of dental floss, will then need to be charged as well via the Lightning port.
Word on the street is they look and feel pretty similar to your standard Apple earbuds, so there's not really anything special to, you know, keep 'em in place. Man, we're all gonna lose these so fast.
Update 12/13/16: Apple Airpods are on sale now, but shipping for pre-orders might take awhile.