I just read an interesting article from Reuters on the level of interest of Europeans and having TV available on their mobile phones. See: TV on cellphone screens? No thanks, say Europeans - Yahoo! News
Personally having had the Slingbox mobile client on my Motorola Q for the last year, I have to admit - TV on demand on a mobile device is pretty handy. Besides killing time in line at the airport or DMV, it's been a great way to stay connected with the local newscasts while traveling. When the Sabres were making their playoff run last year, I could draw a small crowd around my tiny screen to see the game live.
I've also had a Video-capable iPod for the last year and did spend some money on a few videos for long flights last summer. In my mind I could justify the expense as "part of the vacation cost", but having to pre-meditate the purchase and download was a drag. I'm not sure how many times I'll be doing that in the future.
The challenge is figuring out how mobile TV can make money here in the US. After experiencing it for a while, I think it will happen outside the phone operator's domain. Frankly - they make money on transport, not content. The mobile operators will use mobile TV as justification for an expensive data plan that is required to use YouTube or other content providers, not on the content itself.
Will mobile TV change everything? Yes, but I think it will drive data traffic to ever increasingly capable mobile devices. That's where the money is.