It's the same as for you . . . a nice treat, just don't overdo it. Stay away from chocolate, of course, although there isn't enough true chocolate in most ice cream to hurt most dogs; still, better safe than sorry.
My Bear used to love to stop for a dish of ice cream when I'd take him to Gatlinburg. The shop owner always gave him free ice cream; Bear was good for business, lol, people would stop to get ice cream and watch the big wolfy looking pooch eat his!