OrbLive is probably the best app to hit the iPhone yet.
There is so many variables to get it to work since its reliant on your pc at home with a TV card that its best to go over to forums.orb.com. Read their "READ THIS FIRST" post to see if that can resolve your problem then ask if you still cant get it.
I just got it to work on my system. Streaming live tv from my desktop PC (winxp, a64, + ati 550pro tv card) to my iphone is pretty cool. Didn't have to do anything special, it just worked after basic configuring.
Never have to pause tv or miss part of tv shows when you go to the restroom again. Heh.