I'm not quite sure if this is what you're getting at, but I said a few months back that Location-Free viewing would be a great companion feature for the AppleTV. I'd love to be able to que up my home movie collection from any TV. Sure, it wouldn't be an instant download, but I think it's doable.
Errr sorry maybe I should have explained more! With PS3 you effectively have a the slingbox functionality built into it, so you can stream your movies and music to a remote location (to the PSP) at the moment there isn't a pc or mac client.
You will also be able to stream live and recorded TV to, and schedule programs to record remotely.