OK, I've installed the EyeTV software on my AppleTV now, and mounted my home dir from my iMac.

I can now play my EyeTV recordings directly, full screen, on my AppleTV.

This is ace, as it saves me having to convert all my recordings first - taking ages, and losing quality.

As my EyeTV hardware is Firewire, I can't try that out, but I'm now very tempted to get an EyeTV Hybrid or Diversity.