I'm doing exactly this as well, but I think it's a good idea for companies like Apple to make such a feature accessible to end users. Many users just make do with their ISP provided address, or services such as gmail or hotmail etc., so giving them support for this kind of feature would be a great way to reduce spam.In any case, I already have the perfect spam solution similar to what Apple is doing here. All it takes is to purchase your own domain name and use the catchall email feature with forwarding to your real email address.
It should however be taken a step further with some kind of interaction with the server and your mail client. For example, by adding a special header your mail client can know if your server supports this feature, thus if I were to suddenly receive an e-mail to walmart@mydomain.com then if I mark it as junk in Mail, instead of handling it locally Mail could optionally tell my server never to accept mail from that address ever again. Obviously it needs some means of cancelling that as well, but it could be a good thing to do.
Like I say, I'm using a catch-all address, but my provider also supports garbage addresses that just immediately delete messages, so I can set such an address for anything that looks like an attempt to guess a valid address. For example admin@mydomain.com seems to be quite a popular one as historically a lot of sites had this.