I had MobiTV on my LG phone with AT&T before I got my iPhone. $9.95 per month, and it had both live TV (Discovery Channel, TLC, etc.) and videos. You had to have 3G, though. It worked well as long as I was in a 3G area (like Chicago, where I live - it was
terrible on road trips!), but it drained the battery in less than an hour from full charge to dead. About 50 channels; it was kinda cool.
Now I have Elgato's EyeTV Hybrid (about $150) and iPhone Remote (free - Google it to download it). I can login to my computer from anywhere using my iPhone, and watch tv shows I recorded (free OTA HDTV using a $21 indoor table-top HDTV antenna or cable, since I have both hooked up to my Hybrid), and I don't have to pay anything extra.

I can watch it live, but there's no sound, so that's not great. I still have to figure out how to get sound live - then it would be perfect! It works
great with stuff I record, though! HD stuff looks like HD on the iPhone, too.
The screen is way better on the iPhone, it doesn't drain the battery any more than using Safari normally does, and I love it! I can use any program on my iMac from my iPhone with iPhone Remote, too. It's awesome! Of course, where I am, Edge isn't all that slow, so it's fine for me. Maybe for those in areas where Edge crawls it wouldn't work so well.