If you cancel more than 31 days out, they just go back into your account. But its wrong to say there isn't any penalty. Points have a limited life, and the closer to the end of your use year they get, the harder they can be to use. For instance, my use year is April - I get my points April 1st and any unused points expire March 31st. If I book a trip for Febuary and cancel it in December, those points just return to my account - but I have to use them by the end of March - that may be tough.
At 30 days they go into holding and can only be used to make reservations within (I think) 60 days. Once again, that tends to limit their usability.
This is why some members who rent points have cancellation penalties that kick in pretty much the moment they get the check.