Well, since my earlier post I've taken the plunge and bought an Apple TV. What motivated me was a combination of buying an HDTV and the wife-acceptance-factor.
The Mac Mini was a neat solution, but EyeTV isn't quite ready for prime-time as a media centre solution... It's almost there, but there are still too many little quirks for a non-technical user (like my wife) to want to put up with.
Additionally, in my case I basically got another computer back for the price of an Apple TV, since I moved the Mac Mini back into my home office, and now use it on the back-end to sync and stream to the Apple TV, as well as for a multitude of other tasks.
The bottom line is that the Apple TV is a great solution if you live in iTunes for your audio and video content, and have your photos in a compatible application like iPhoto, or even just in a decently-organized folder structure.
For thedaveman, it sounds like an Apple TV would be a good fit. You'll need to sync the photos to the Apple TV's hard drive (this works in the same way as it does for an iPod), as it won't "stream" photos, but music, videos and podcasts can all be streamed and/or synced.
In my case, I have an 802.11n network that I put in for the Apple TV, so my streaming speeds are more than acceptable. I primarily sync content to the Apple TV just to keep a short-list, since I have a fairly large content library that can be a pain to dig through. So I keep my favourite music and recent purchases synced to the Apple TV, as well as any TV shows that I'm following (either from iTunes or self-converted from EyeTV recordings, which I still do on the Mac Mini on the back-end).
So far I'm very happy with the Apple TV, and best of all it "just works" without any fuss. Again, however, you have to be fairly solidly into the whole iTunes ecosystem in order for it to really fit into your world. As arkstfan points out, it won't handle video formats like Real or WMA, and can't stream from Internet sources at all (beyond the "top-ten" lists and movie trailers that are built-in to the menus).