We wrote about Apple's recycling program when it was first announced, and now it is in full effect, yo. All you have to do is buy a new Mac and then you can participate in the program. You either get an email (if you purchased your Mac from the online Apple store), or you'll get asked if you want to participate at the store. You'll then get an email with instructions. Pack up your old computer (Mac or PC), take it to a FedEx location (with that email you got) and that is all!