In reply to Šljiva:
It's charged - and they generally use helicopters, so it can be very pricey. 6000CHF was the cost of 1 rescue I've seen. So decent insurance is definitely recommended!
Having said that, it's a great rescue service that is funded by people who pay a yearly membership. you can support by being a patron, see -
http://www.rega.ch for details.
Just spotted this is in the ski forum - in resorts rescue is often by piste patrol. In my experience sometimes they charge and sometimes they don't. They still use Rega if they feel it's needed and then you'd want to be well covered.
Post edited at 22:17