No, not WebTV (or MSNTV, as it's now known)...no, not any device that lets you view the web on your TV.
...but a web-browser for TV production companies to use that render web-pages in an acceptable manner for broadcast quality television.
I.E. not showing screencasts of IE over the TV, the picture is terrible and you can't read the page they're showing anyway.
A quick way to develop this would be to use an existing, proven, rendering engine, say Presto (which is adept for "unconventional" platforms), then raise the font-size, maybe use a User stylesheet, and no browser-chrome would be shown on the screen.
Reckon any company might buy it? I can see Discreet/AutoDesk making it part of their real-time systems solutions.
Eventually everything will be vector. Zoom in zoom out. Another problem is the resolution on the LCD/Plasma screens are not the same everywhere. Nor is the colour depth. I don’t even think you can detect the size of the screen from the browser if a TV is used,
You’d be better off reformatting the content to vector, and presenting it that way.