I was round at at friends last night who just picked up a Sony Bravia TV with a built in freeview|HD tuner. They have a satelite dish but no UHF or VHF aerial. Anyhow he tried plugging the TV into the wall socket that connects to the dish, and manages to get two of the three multiplexes. I checked the signal strength and he gets 100% on the Kordia and Mediaworks multiplexes, but nothing on the TVNZ one.

Given where he lives I'm more than suprised he can get anything without a decent aerial.