Our last work truck was a hail damage got almost 25% off asking price, pretty much a 2 year old $32K truck for low $20K's.  Most of the dents have worked out, real nice thing is you aren't scared of hail if it hits while you are out.  Plus since it wasn't totaled by the dealer it still kept the powertrain warranty.  Not sure if I'd do it on a new one or not might not have enough depreciation taken out even with the damage.  If you looked at the truck today you'd be hard pressed to know it has been through two golf ball to baseball sized hail storms and it is an '08, helps that it is white.

You are right the dealer pretty much marks it down the same amount the insurance is going to pay them for it so they still get original asking price.  In our case they said they'd fix all the body work and sell for the original asking price if we wanted.  Best $8K we ever saved.