"No-Key" cars?

My SIL flew into Houston the other day on business, and came by to visit in a rented Taurus. We went to lunch and I noticed that the car did not have a traditional key, just a sort of fob and a start button on the dash; akin to his Benz that I drove when I visited him a year ago. I was surprised that a mid-priced car now had the technology. The cost must have really gone down.



My question is, are they better than traditional keys, or have the thieves already found a way to beat them?



How do they work? Just a variable frequency like a garage door opener?