Originally Posted by Play Care:
If I can get out to shovel with the kids we do. But mostly I remind parents to wear boots ifs it's snowed during the day as I can't guarentee I'll be able to do it. I will leave the shovel out and they can have at it if they feel inclined 
I do have parents sign a waiver acknowledging that use of the driveway and walkway during the winter is at their own risk. While it won't prevent me from being sued to begin with, it may prevent them from getting anything out of it.
It doesn't protect you. Where I live, there's like time limit for shoveling before you get tickets, I think after two tickets, you get a fine. It's under 24 hours, but I forget the exact number. I either have my husband do it or pay someone locally to do it. Also, they can still sue you for injury.