I got a postcard recently announcing the addition of them at the OKC airport, offering you 500 miles for the first time you used it. The fine print did say it was a one time bonus.

This may have been targeted as I have not been getting any bonus for using the machines at other airport. If memory serves me correctly American put a cap on the maximum you could get from the kiosk check in, something like 2,000 miles if I remember correctly, and I think that was last year.

I don't think there is any bonus for using the machines, or I should say I haven't been receiving any miles for using the things.