For the audio bits, you clearly want a receiver that can switch HDMI. That will allow you to have only a single HDMI cable going to your TV. Exactly which receiver, I'm not sure. That probably depends on your speakers. Also worth noting, some receivers are now built using "class-D" amplifiers (i.e., they use efficient switching power supplies), which mostly means much smaller packaging and much less heat output. See, for example, the Pioneer Elite "SC" models. Depending on your situation, that could be a feature worth looking for.

Many receivers now have Ethernet jacks, USB ports, and other attempts to converse with the digital side of your life. So far as I can tell, none of this is going to work as beautifully as an AppleTV. The feature I'd like to see more is USB sound card support, allowing your HTPC to speak to your amp digitally in a clean and simple way. The aforementioned Pioneers seem to support USB for talking to iPods and for accessing music on memory cards, but otherwise nothing mentioned on the web page.

BluRay, of course, will require a dedicated BluRay player, and there's no easy way to rip and stream BluRay media (yet... the hacker types are certainly working on it). Some BluRay players are growing Ethernet jacks and also trying to compete with the AppleTV and whatnot.