I'm not sure if AppleTV will ever be a full blown computer. The concept behind AppleTV is a network bridge. For the same reason we don't package 4 port routers into client workstations, I don't think it's useful to bog down a multimedia bridge with processor operations not relating to the serving of content over the network.
The patents Apple has been filing in relation to AppleTV and future iterations thereof revolve around this detached "head unit" idea where, in the future, AppleTV will bridge multiple input and output devices over the LAN. These may include streaming content to and from iPhone, multiple televisions throughout the house, PDA devices, subnotebooks, etc. This is the way to do it... having resources wholly dedicated to bridging the content and providing global onscreen menuing functions to output devices.
The idea here is that if you want to add functionality like a DVR or a DVD player, you can do it modularly, leaving AppleTV alone. Not everyone, myself included, wants to take the step backward and incorporate removable media into a network based media distribution system. I prefer to keep all content stored on hard drives and streamed locally and globally. It might even turn out that AppleTV will help facilitate streaming of LAN content to mobile devices connecting to the net through WiMAX/4G, etc.
This is Apple's vision for the future... extending the boundaries of the "digital hub" strategy out to your car, your pocket, anywhere...